World Geology

Islam And Geology

How do you present proof of this religion to those who do not speak the language of the Arabs or know anything about the inimitable eloquence of the Qur’an? Is it the only way for them to learn this language of the Arabs and to master its sciences? The answer, of course, is no. Allah, may He be Glorified and Exalted, has shown mercy to them and to all other generations by sending the appropriate evidence to all mankind, irrespective of their different races, languages, and times.

We have Professor Palmer who is one of the foremost geologists in the United States of America. He headed a committee which organized the Centennial Anniversary of the American Geological Society. When we met him we presented the various scientific miracles in the Qur’an and Sunnah, he was greatly astonished. I remember a pleasant anecdote when we informed him that the Qur’an mentions the lowest part of the earth and states that it is near Jerusalem, where a battle took place between the Persians and the Romans.

Allah, may He be Exalted and Glorified, said in the Qur’an:

Alif Laam Meem, the Romans have been defeated, in the lowest part of the land (adnal-ardh), but after defeat they will soon be victorious. (Qur’an 30:1-3).

The term adna means both nearer and lowest. The commentators of the Qur’an, May Allah be pleased with all of them, were of the opinion that adnal-ardh meant the nearest land to the Arabian Peninsula. However, the second meaning is also there. In this way, the Glorious Qur’an gives one word several meanings, as described by the Prophet Muhammad (sallallahu ‘alaihi wa sallam) when he said:

I have been given the most comprehensive words. [Al-Bukhaari and Muslim]

When we investigated the lowest part of the earth, we found that it was exactly the same spot that witnessed the battle in which the Romans were defeated. When we informed Professor Palmer about this, he contested saying that there were many other areas which are lower than the one referred to in the Qur’anic verse. He gave examples and names of other areas in Europe and in the United States. We assured him that our information was verified and correct. He had with him a topographical globe that showed elevations and depressions. He said that it would be easy with that globe to ascertain which was the lowest spot on earth. He turned the globe with his hands and focused his sign on the area near Jerusalem. To his astonishment, there was a small arrow sticking out towards that area with words: The lowest part on the face of the earth.

Professor Palmer was quick to concede that our information was correct. He proceeded to speak, saying that this was actually the lowest part of the earth.

Professor Palmer: “It took place in the area of the Dead Sea which is up here and interestingly enough the labeling on the globe says “the world’s lowest point.” So it certainly is supported by the interpretation of that critical word.”

Professor Palmer was even more astonished when he found that the Qur’an talks about the past and describes how creation first began; how the earth and heavens were created; how the water gushed forth from the depth of the earth; how the mountains were anchored on land; how vegetation first began; how is earth today, describing the mountains, describes its phenomena, describes the changes on the surface of the earth as witnessed in the Arabian Peninsula. It even describes the future of the land of Arabs and the future of the whole earth. At this, Professor Palmer acknowledged that the Qur’an is such a wondrous Book which describes the past, the present, and the future.

Like many other scientists, Professor Palmer was hesitant at first. But soon later he was forthcoming with his opinions. In Cairo, he presented a research paper dealing with the inimitable aspects of geological knowledge contained in the Qur’an. He said that he did not know what was the state of the art in the field of science during the days of the Prophet Muhammad (sallallahu ‘alihi wa sallam). But from what we know about the scanty knowledge and means at that time, we can undoubtedly conclude that the Qur’an is a light of divine knowledge revealed to Muhammad (sallallahu ‘alaihi wa sallam). Here are the concluding remarks of Professor Palmer:

“We need research into the history of early Middle Eastern oral traditions to know whether in fact such historical events have been reported. If there is no such record, it strengthens the belief that Allah transmitted through Muhammad bits of his knowledge that we have only discovered for ourselves in recent times. We look forward to a continuing dialogue on the topic of science in the Qur’an in the context of geology. Thank you very much.”

As you have seen, here is one of the giants in the field of geology in our world today, coming from the United States of America. He does not hesitate to admit and to come forth with his opinions. But he is still in need of someone to point the truth out to him. Both westerners and easterners have lived in the midst of the battle between religion and science. These battles, however, were inevitable, because all previous messages have been distorted. Thus, Allah sent the Prophet Muhammad, (sallallahu ‘alaihi wa sallam), with Islam in order to correct that which had been corrupted.

Someone may ask: ‘How will these people accept what we tell them when we are materially inferior to them and we do not follow our religion closely?’ My reply to them is that knowledge increases the awareness of one who acquires it. People of knowledge care only to look at the facts, not at the outside picture. The wealth of Islam today is precisely this knowledge and scientific advancement. Modern science can but bow its head in reverence to the book of Allah and to the Sunnah of His Prophet (sallallahu ‘alaihi wa sallam).

The primordial nature, Al-Fitrah, in which Allah created man does not attain tranquility except by means of Islam or eeman (faith). Those who do not have eemaan (faith) are in a constant state of uneasiness and confusion. Moreover, the atmosphere of freedom in the West helps Western scientists to express what they believe without any fear or timidity. We have heard them in many of these episodes confirming and recognizing the miracle of this age, the Qur’an, which will remain living until the Last Hour.

General Geology New Concepts

General Geology New Concepts <====Click Here

Geology means, literally, the study of the Earth. Explore this section to understand the structure of the Earth and its surface features, what causes earthquakes and tsunamis, and why volcanoes form and erupt. Learn about minerals, which form the building blocks of rocks, and how rocks are made and destroyed. Learn about Earth’s fascinating history, the variety of life forms which have roamed the surface over the millennia, and the dramatic changes that have happened over Earth’s long history.

Arabian Plate

The Arabian Plate is one of three tectonic plates (the African, Arabian and Indian crustal plates) which have been moving northward over millions of years and colliding with the Eurasian Plate. This is resulting in a mingling of plate pieces and mountain ranges extending in the west from the Pyrenees, crossing southern Europe and to Iran forming Alborz and Zagros Mountains, to the Himalayas and ranges of southeast Asia. [1]

The Arabian Plate consists mostly of the Arabian peninsula; it extends northward to Turkey. The plate borders are:

The Arabian Plate was part of the African plate during much of the Phanerozoic Eon (Paleozoic – Cenozoic), until the Oligocene Epoch of the Cenozoic Era. Red Sea rifting began in the Eocene, but the separation of Africa and Arabia occurred in the Oligocene, and since then the Arabian Plate has been slowly moving toward the Eurasian Plate.

The collision between the Arabian Plate and Eurasia is pushing up the Zagros Mountains of Iran. Because the Arabian Plate and Eurasia plate collide, many cities are in danger such as those in south eastern Turkey (which is on the Arabian Plate). These dangers include earthquakes, tsunamis, and volcanoes.

Arabian basin

The vast hydrocarbon accumulations of the basinBasins of the Upper Jurassic are directly tied to the tectonic evolution of the Arabian Plate. This section attempts to trace the development of the northeast margin of the Arabian Plate a developmentaccumulation the vast accumulation of the source, reservoir, and seal rocks of the Upper Jurassic and to the migration and trapping of these vast hydrocarbon reserves. The Arabian Plate tectonic history can be subdivided into six tectonic phases that shaped its geology. These include:

  • Pre-Cambrian
  • Ordovician-Silurian Glaciation / de-Glaciation
  • Carboniferous (Hercynian Orogeny)
  • Early Triassic (Zagros Rifting)
  • Late Cretaceous (First or Early Alpine Orogeny)
  • Tertiary (Second or Late Alpine Orogeny)
  • Neogene Separation from Africa.

The geological map of the Arabian Plate illustrates that divergent margins are forming in the spreading centers of Red Sea and Gulf of Aden to the west and southwest of the Arabian Plate. The South and southeast of the Arabian plate is bounded by the Owen-Sheba intra-oceanic transform fault. An active convergent margin lies to the north and northeast with Turkey (Bitlis sutures) and east within Iran (Zagros Mountains) where the Arabian plate is thrusting beneath the Eurasian plate. The Dead Sea represents a transform strike-slip fault zone to the northwest of the Arabian Plate

Pre-Cambrian

The oldest portions of the Arabian plate formed in the middle to late Proterozoic (800-650 Ma) when a series of island arcs and micro-continental fragments accreted against the northeastern margin of the Pan African craton to form the Gondwana super-continent. The primary crust of the Arabian shield is composed of a combination of several constructional units, each of which was formed by an intra-oceanic island arc terrain consisting of an andesitic assemblage of meta-volcanic rocks and a dioritic suite of plutonic rocks. Each closure and arc collision led to deformation and ophiolite obduction (north-south units) and was culminated with microplate and continental collision at about 640 Ma. The last Precambrian orogenic event was concluded with the development of Hormuz saltbasin in eastern Arabia and is characterized by horsts and tilted fault blocks trending NNE-SSW (Beydoun, 1991).

Ordovician-Silurian Glaciation and de-Glaciatio

The Late Ordovician was characterized by the expanding of the polar glaciers across Gondwana and most of western parts of Arabia (Husseini, 1991).

 

In the Early Silurian, sea level rose in response to deglaciation and resulted in the widespread deposition of the upward-coarsening Qalibah Formation, which consists of a lower Qusaiba member and an upper Sharawara member (Mahmoud et al., 1992). The Qusaiba member at the base of Qalibah Formation is an organic-rich shalecorresponding to a maximum flooding surface. This “hot shale” unit ranges in thickness from 20-70 m. On the basis of carbon isotope and biomarker data, the basal Qusaibashale is believed to be the principal source for the low-sulfur, light oil discovered in Paleozoic reservoirs of central and eastern Saudi Arabia (McGillivray and Husseini, 1992). According to Vail (1977), a hiatus associated with a global sea-level drop occurred in the late stages of Silurian.

Late Devonian to the Early Carboniferous

During late Devonian, a Hercynian Orogeny structural event initiated the uplift of central Arabian and tilted the Arabian plate eastward, exposing Devonian and older rocks to erosion and transforming the northeast Gondwana margin from a passive to an active margin (McGillivray and Husseini, 1992). The Arabian Plate was also rotated through 90o in an anticlockwise direction. This tectonic event resulted from the collision between Africa and the North American-North European continent. This event produced a significant hiatus (pre-Unayzah unconformity” (PUU) or the Hercynian unconformitywhich produced significant uplift and erosion at the Ghawar region (McGillivray and Husseini, 1992). During this time the Unayzah Formation (50-300 m thick) accumulated and consists of fine to coarse-grain fluvial/alluvial sands that filled the relict topography formed by the differential erosion of the Hercynian structures. The Unayzah Formationforms the principal pre-Khuff hydrocarbon reservoir in Southern Ghawar area (Paleozoic) and central Arabia (Hawtah field).

The NS-trending compressive Hercynian orogeny resulted in the forming or rejuvenation of the Central Arabian Arch, which is overprinted by the basement, cored Ghawar anticline (Konert et al., 2001). The movement of these arches persisted into the Jurassic and later.

Late Permian through the Jurassic Zagros Rifting

In the Late Permian, the Arabian-Gondwana/Iranian-Laurasia super continent was fragmented when the crust was stretched, and by the Early Triassic eventually rifted along the Zagros line to form the Neo-Tethys Sea (eastern margin of the Arabian Plate) (Beydoun, 1991). During the Jurassic the Arabian plate was relatively tectonically stable and was located at the Equator enabling the development of a wide shallow shelf on the western passive margin of the Neo-Tethys on which carbonates accumulated over the shelf and inner platform. Most of the Arabian Gulf petroleum source-reservoir-seals accumulated during the Jurassic and Cretaceous.

The climate became more humid towards the end of Early Jurassic. As a result, evaporites deposition was rare. Intrashelf depressions such as the Gotnia, the South Rub’ AlKhali, and the Arabian Basins were created as a result of tectonic differentiation and rising sea level.

The major formation of the Arabian platform was initiated in the Late Callovian, and caused the deposition of the organic rich rocks that form the major source formation in the anoxic intrashelf basins of the Middle East (e.g., Gotnia Basinand Arabian Basin). The carbonate deposition on the shelf kept pace with changes in sea level until the end of Jurassic when the major evaporitic seals were deposited during a fall in sea level as the climate became predominantly arid.

Middle to Late Cretaceous Alpine Orogeny

The onset of the Alpine-Himalayan orogeny started in the late Cretaceous. The Neo-Tethys began to close and as a result of compression and foredeep developed in eastern Arabia. The re-organization of the Indian Ocean spreading centers (as a result of fast northward motion of Indian plate) thrust fragments of ocean crust upon the eastern Arabian plate continental margins (Semail ophiolite of Oman) (Hulver, 2000). This tectonic motion produced a major hiatus of sedimentation across the Arabian plate and the Pre-Aruma unconformity (PAU). Additionally, the “Hercynian” structures were rejuvenated and started forming the major eastern Arabian petroleum traps (e.g. the Ghawar anticline) (Beydoun, 1991).

Tertiary (35 Ma) Zagros Orogen

Compression between Arabia and Asia resulted in the initiation of the Zagros Orogeny. The Arabian plate converged and subducted beneath Iran and caused the Arabian plate to tilt slightly to the northwest to form a series of anticlines and thrusts in the Zagros Mountains. The Arabian Gulf foreland basin, which lies beneath the western edge of the Zagros thrust, was created as a result of this collision. The major Hercynian structures continued to grow leading to the completing the formation of the major oil traps (Hulver, 2000).

Stratigraphy Setting of Russia

Stratigraphic tables and applied ages

  • Stratigraphic overview tables are schematic. They are meant to show the subdivision, geographic extension and approximate chronological correlations of units.
  • Age indications on the stratigraphic overview tables are rough and should be used with care. In cases where diverging age interpretations exist, only one interpretation is shown in the tables. See age sections in the lexicon parts for more comprehensive information.
  • The ages and age boundaries of the units are indicated in accordance with existing data, but are admittedly schematic. Possible diachronous boundaries are drawn straight unless there are reliable data that document the diachronism.
  • The appendix contains biostratigraphic tables applied to Svalbard’s Late Palaeozoic and Mesozoic successions. The biostratigraphic zonation of the Cenozoic succession is not known precisely enough. See remarks in the age sections of thelexicon part.

1.3.5 Type localities and type sections

  • All type sections in this site are redrawn from the originals according to a technical standard established for this purpose at Norsk Polarinstitutt.
  • A fold-out legend for all type sections is contained at the inside of the back cover.
  • The extremely varying standards, quality and scientific foci of the original sections made it impossible to redraw them according to a scientifically uniform standard. This means that differentiation made in some sections (e.g. sandstone, silty sandstone, siltstone, sandy shale, shale) may not be made in others (e.g. sandstone, siltstone, shale). In most cases, the original quality of information is maintained, although generalisation was undertaken where the purpose of technical standardisation required this.
  • As a result of this, for instance, some original sections show a very rough grain size classification, different ways of particle classification (e.g. for carbonate rocks), or none at all which would satisfy the presently accepted standard grain size scale. These sections are adapted to the standard scale, with the note “grain size approximate”.
  • Almost all redrawn sections have been checked and accepted by the authors of the originals or by a research partner or supervisor. For a few older sections, this was, of course, not possible.
  • Where newer and more informative logs of a previously defined type section existed, these new sections are used here. The reference to the original definition is only shown in the text.
  • Different kinds of type localities and sections used in this site:
    • Stratotype: The main type locality and section which presently define the unit. Due to the often poor documentation of other previously defined type localities, the term neostratotype is not applied, but previously defined stratotypes are mentioned in the text.
    • Hypostratotype: The second or third type locality of a unit that documents major regional variations. Hypostratotypes for some units in Svalbard are defined herein for the first time.
    • Boundary stratotype and Unit stratotype: If a unit does not have a documented locality where both its base and its main body are sufficiently represented, type localities for the lower boundary and the main unit body are defined separately. The use of boundary and unit stratotypes is here introduced to Svalbard stratigraphy.
  • The name-giving localities of stratigraphic units in Svalbard rarely coincide with their type localities. The reason for this is that unit names mostly have not been changed since their first appearance or definition in the geological literature, when type localities were not sufficiently documented. Later, better type localities were often found and documented in different places. Another reason may be the lack of geographical names in the area of the type locality, or the use of the same type locality for several units.
  • Availability of cores from type wells: For most Mesozoic type wells, apply to the Norwegian Petroleum Directorate (NPD). For cores from wells containing the letter U in the well number, apply to SINTEF Petroleum Research. For cores from Cenozoic type wells, apply to Kings Bay A/S in Ny-Ålesund, Svalbard.

1.3.6 Maps

  • The overview maps show the distribution of stratigraphic groups (Fig. 1-04), major structural elements (Fig. 1-05), and the position of all detailed maps and the names of major geographical areas frequently mentioned in the text (Fig. 1-06).
  • The other maps show the geographical distributions of formations. Sets of maps show the formations of Late Palaeozoic, Mesozoic and Cenozoic age, while rocks of other ages are only subdivided into major complexes.
  • For the geographical distribution of units with a lower stratigraphic rank (members, beds) the reader is referred to the text. The exact distribution of many of these units is still poorly known.
  • Ages indicated roughly in the legend of these maps are meant for general orientation. See age sections in the lexicon parts for more comprehensive information.
  • The maps are not tectonic maps. To keep the map information clear, only faults that have influenced either the deposition of the respective stratigraphic interval or its present outcrop pattern, are shown. For instance, faults bounding Carboniferous troughs are not shown on the maps belonging to the chapters on Mesozoic or Cenozoic stratigraphy, while faults displacing only Mesozoic and Cenozoic rocks at the surface do not occur on the maps in the Late Palaeozoic stratigraphy chapter. For fault symbols used on the detailed maps, see legend on the overview maps (Figs. 1-041-05).
  • The positions of all type localities are indicated by the ID number of the respective unit (section 1.3.3). Type localities which are not provided with a stratigraphic log are also shown in this way.
  • Most geographical names used in the text, including name-giving or type locality names, are shown on the maps.
  • References to sources of map data are too abundant to be indicated on the maps. Most information is referred to on the bedrock maps published by Norsk Polarinstitutt, including preliminary editions.

1.3.7 Correlations with the geology of the Barents Sea Shelf

  • During the committee’s work on the lithostratigraphic nomenclature, correlations with the stratigraphy of the western Barents Sea Shelf were considered important. Hydrocarbon prospecting in the western Barents Sea has been going on since 1980, and with the expected future developments there, the amount of stratigraphic names will increase. Svalbard is often used as a reference and training area by offshore geologists working in the Barents Sea. It is the committee’s opinion that the lithostratigraphic nomenclature systems should clearly show the relationship between the onshore and offshore development and that the framework of stratigraphic groups should reflect this relationship.
  • The Late Palaeozoic stratigraphic nomenclature of the offshore areas is presently being worked on by another committee in close co-operation with NSK. Its work is not yet concluded, but there is a general consensus that the framework at group level will be applied from Svalbard, while an additional group is defined in the western Barents Sea, with only one formation represented onshore on the island of Bjørnøya. Available data points on the Upper Palaeozoic of the Barents Sea Shelf are still sparse.
  • The nomenclature of the Mesozoic stratigraphy in the western Barents Sea has preliminarily been established in connection with the present work. Abundant data are available, although published data are mainly restricted to the Hammerfest Basin. The overall group framework proposed here will probably be applicable for a long time ahead, while adjustments or additions at lower levels are expected. Work on the offshore Mesozoic nomenclature has made significant progress and Mesozoic offshore formations are included in the present volume.
  • The stratigraphy of the Cenozoic offshore basins is not yet well enough known. Cenozoic offshore basins probably developed separately from those exposed onshore.

1.3.8 Change of place-name segments

  • Place names in Svalbard have changed significantly throughout history. One reason is the international use of Svalbard through the last centuries. Norway did not start to execute her sovereignty earlier than 1925 (according to the Svalbard Treaty of 1920), when names from other languages gradually started to be translated into Norwegian. Even later, Norway started to pursue the policy of naming – and renaming – places according to spelling in the less wide-spread of the two Norwegian languages, Nynorsk. Many modern, revised spellings did not occur on maps or publications previous to the 1990s. For these reasons, many place-name segments of stratigraphic units do not coincide with the spelling of the respective place names on modern maps, which is disadvantageous.
  • SKS has adopted the new spellings for those place names where changes were minor, and where the original name is easily recognised (e.g.: Petrelskardet Formation – Petrellskaret Formation).
  • SKS has changed incomplete place names into complete ones in order to avoid formation names with a first segment reflecting, for instance, a person rather than a mountain (e.g.: Vegard Formation – Vegardfjella Formation).
  • SKS has not adopted translations of names from, for instance, original English place names (ex.: Wood Bay – Woodfjorden, for a Devonian formation), or other major changes where the original place name would then not be easily recognised.

1.3.9 Lower boundary definitions and descriptions of geological units

  • This lexicon is attempting to standardise descriptive data from a huge variety of original sources and authors. The various geological units have been investigated and described for different purposes and with a varying quality in the geological literature. It was therefore not always possible, on the basis of existing data, to achieve a consistent way of description. So, for instance, while some units may lack a reference to an interpretation of the depositional environment, others may lack sufficient data on lateral facies variations, etc.
  • To avoid much repetition, some features may be described for a superior rank unit (e.g. formation), without being repeated in the description of the inferior rank units (members), or vice versa, depending on what appeared to be most appropriate. The user of the lexicon is therefore asked always to check superior and inferior rank units in order to find the requested information.
  • A good definition of its lower boundary is an important property of any geological unit. The great variety of authors of different nations defining these units in Svalbard may result in an inconsistent quality of lower boundary definitions. In many cases, geological units were defined without a proper definition of their lower boundary. These units may still have survived history and be accepted by present geologists as “good” units, simply because they designate characteristic rock successions. Many lower boundary definitions, a demand of modern lithostratigraphy, have therefore been added by the authors of this lexicon as precisely as possible from the existing data. For a number of units, especially for those with interfingering contacts or transitional boundary features, these definitions may appear rather arbitrary.

1.3.10 Notes on references

  • The literature references cited in this site are preferentially confined to work from the 1920s onward. The reason is that earlier authors often did not subdivide the stratigraphic succession in a way that makes their work relevant for the nomenclatorial issues treated in this site. It must still not be forgotten that the geological description of Svalbard started more or less in the 1860s, and the first two generations of Svalbard geologists provided significant pioneer work. To find references to this, the reader is referred to the bibliography.
  • A relatively high amount of units have been defined and/or described on the basis of previously unpublished data. The reason for this is the enormous amount of data collected by petroleum geologists and only contained in internal reports of their companies, and a large amount of unpublished theses. For future reference to these units, the present lexicon is to be considered as the original publication, although reference to the unpublished source always should be provided in addition. The use of unpublished data in this case should not be problematic; the respective unit definitions have been extensively reviewed by the entire subcommittee (authorship of the respective lexicon chapter), prior to the reviews by SKS, NSK (Norwegian Committee on Stratigraphy), and final referees.

1.3.11 Explanation of place names

  • Place names in Svalbard which have been used for stratigraphic unit names, have either a descriptive meaning, or are from persons, vessels, etc. Descriptive meanings are translated in the lexicon part of the site, because these names may have geological implications.
  • For other place names, and for more information about the names, the reader is referred to ‘Place names in Svalbard’, Norges Svalbard- og Ishavsundersøkelser (1942) and Orvin (1958), both reprinted by Norsk Polarinstitutt (1991).

Explanation of common place-name endings:

   – bekken: Creek
– berget: Mountain
– breen: Glacier
– bukta: Bay
– byen: Town
– dalen: Valley
– egga: Crest
– elva: River, Creek
– fjella: Mountains
– fjellet: Mountain
– fjorden: Fiord, Inlet, Firth
– flya: Plateau
– fonna: Ice Cap
– halvøya: Peninsula
– hamna: Harbour
– haugen: Hill
– hatten: Hat
   – heia: Hill
– heim: Home, Hut
– hornet: Horn, Peak
– høgda: Hill
– huken: Point
– isen: Ice, Glacier
– kammen: Crest, Ridge
– kampen: Top
– kanten: Edge
– Kapp: Cape
– kjegla: Cone
– laguna: Lagoon
– Land: Land
– neset: Point, Cape
– nuten: Summit
– odden: Point, Cape
   – øya: Island
– passet: Pass
– pynten: Point, Cape
– ryggen: Ridge
– salen: Saddle
– såta: Haystack (cone-shaped mountain)
– skaret: Notch, Pass
– sletta: Plain
– stranda: Beach
– sund: Sound
– tangen: Point, Cape
– tind(en): Peak
– toppen: Summit
– vågen: Bay
– vatnet: Lake
– vika: Bay/Cove

1.3.12 Transliteration of Russian names and references
Russian names and references correspond to the ISO (International Standard Organisation) transliteration, which – with a very minor deviation – is also used in the International Bibliographic System. The advantage of this transliteration compared with national transcriptions, such as the English transcription, is its reversibility. Russian names transcribed in English or other languages cannot unequivocally be transcribed back into the Cyrillic alphabet; this may cause problems when inquiring for authors, or when looking for place names on Russian maps. Unfortunately, various electronic databases and international journals have adopted the English transcription. For this reason, a onversion table is added below (Fig. 1-01).

Fig. 1-01: Conversion table for Russian Cyrillic letters, ISO transliteration and English transcription. Be aware that conversion is only valid from Cyrillic or ISO to English, but not vice versa.

      Cyrillic
      ISO
      English
      a       a       a
      б       b       b
      в       v       v
      г       g       g
      д       d       d
      е       e       e, ye1
      ë       ë       e, yo1
      ж       ž       zh
      з       z       z
      и       i       i2
      й       j       y2
      к       k       k
      л       l       l
      м       m       m
      н       n       n
      о       o       o
      п       p       p
      р       r       r
      с       s       s
      т       t       t
      у       u       u
      ф       f       f
      х       h3       kh
      ц       c       ts
      ч       č       ch
      ш       š       sh
      щ       šč       shch
      ъ       ”       (left out)
      ы       y       y
      ь       ‘       (left out)
      э       ė       e
      ю       ju       yu
      я       ja       ya

1 if first letter in a word or after a vowel;
2 ий sometimes transcribes “y” in English;
3 in bibliographic transliteration: “ch”


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1.4 Outline of the geological history of Svalbard

1.4.1 Tectonic setting

The archipelago of Svalbard is the emergent northwestern corner of the Barents Sea Shelf, which was uplifted by late-Mesozoic and Cainozoic crustal movements. The area provides a splendid insight into the varied geological structure and geo-historical development of the northwestern Barents Sea since the Palaeoproterozoic. The geological record ranges from possible Archean to Recent and shows a multiorogenic development with prominent tectonic events of Grenvillian (late-Mesoproterozoic), Caledonian (Ordovician-Silurian), Ellesmerian or Svalbardian (Late-Devonian), Variscan (Mid-Carboniferous) and Alpidic (Early-Cenozoic) age.
North of Svalbard, 50-100 km from the shore, a steep passive continental margin with slopes up to 10° (average 4°) forms the boundary with the Eurasian Basin of the Arctic Ocean. Offshore to the west of Svalbard, a 40-80 km wide shelf separates the coast of the main island, Spitsbergen, from a structurally complex oceanic area, the Knipovich Ridge (Talwani & Eldholm 1977). The central part of this ridge is a spreading axis which is segmented by a transform fault system, the Spitsbergen Fracture Zone in the north, and the Greenland Fracture Zone in the south (Fig. 1-02).

Fig. 1-02: Geological overview map of Svalbard and the western Barents Sea Shelf, showing the positions of major tectonic elements. Offshore data are mainly from Sigmond (1992); faults north of the Bjarmeland platform are added from unpublished data (Norwegian Petroleum Directorate, 1998) and refer to the top Permian level. The indicated type wells refer to Mesozoic offshore formations defined in Mesozoic Chapter.

The northwestern shelf corner borders the Yermak Plateau, the northern part of which may be the remainder of an Early-Cenozoic hot spot (Feden et al. 1979). Late-Cretaceous thermal uplift, Early-Cenozoic shoulder uplift along the rifted margin of the developing Arctic Ocean, and subsequent transform movements in a periodically transpressive regime along the western margin may all have their share in explaining the uplift of the archipelago and especially of its western and northern reaches.

1.4.2 Pre-Old Red

The term Pre-Old Red is here applied for the rocks already present under the main Caledonian orogenic phase in the Middle Silurian. The literature on the geology of Svalbard often applies the term ‘Hecla Hoek’ to this basement. There has been confusion about this name due to its original definition (Nordenskiöld 1863) and the later elaborated complexity of the Pre-Old Red strata causing several redefinitions (Orvin 1940; Harland & Wilson 1956; Krasil’ščikov 1970, 1973).
The Pre-Old Red succession is exposed in the west and north of the archipelago. It has long been considered to be mainly the product of the Caledonian orogeny, though distinctive unconformities have been reported from southern Spitsbergen (e.g. Birkenmajer 1975, 1991; Bjornerud 1990) and Nordaustlandet (e.g. Flood et al. 1969; Ohta 1982). Since the late 1980s, U-Pb zircon isotopic age determination has revealed several Precambrian events (e.g. Ohta 1994; Gee et al. 1994). The Pre-Old Red thus has a polyorogenic development: Baikalian movements (600-650 Ma), the Grenvillian tectonothermal event (950-1000 Ma), and indications of earlier events recognised in several areas (ca. 1400 Ma, 1700-1800 Ma, and two or three older ones; Ohta 1992) are followed by two distinct Caledonian foldthrust events, including evidence for an oceanic suture zone in the Western province.
The Pre-Old Red is subdivided into three different tectonostratigraphic “basement provinces”, whose structure, sedimentary record and tectonothermal evolution differ from each other. Their juxtaposition occurred probably during the Caledonian period, though no consensus about the involved mechanisms yet exists (Harland 1969, 1971; Birkenmajer 1981; Ohta et al. 1989; Ohta 1994). After the Middle Silurian, however, Svalbard formed part of the ‘Old Red Continent’.

1.4.3 Old Red (Devonian)

During the Devonian Period, Svalbard experienced the deposition of a vast thickness of Old Red molasse sediments which are mainly preserved in a down-faulted crustal block in northern Svalbard, bounded by the northwestern and eastern basement provinces. The main tectonic overprint and tectonic style of this graben system is related to a Late- Devonian culmination of tectonism, the ‘Svalbardian Phase’, which resulted in contractional movements predominant in northern Svalbard (Orvin 1940). The Svalbardian Phase is normally considered to be a late, post-molassestage phase of the Caledonian orogeny and may be related to the Ellesmerian-North Greenland Foldbelt deformation in the Canadian Arctic and northern Greenland.

1.4.4 Late Palaeozoic

During the Carboniferous Period, Svalbard developed from a site of fault block tectonism with differential sedimentation to a stable shelf that experienced overall subsidence (except for southern Spitsbergen). A local (?) phase of folding and thrusting, only locally recorded on southern Spitsbergen, occurred possibly in the Visean (‘Adriabukta event’: Birkenmajer 1964; Dallmann 1992). The main fault block movements occurred in the Bashkirian and Moscovian, resulting in a new constellation of troughs, mainly halfgrabens, with a syntectonic sedimentary record, developed along older tectonic lines (Gjelberg & Steel 1981). With waning tectonic movements in the later Carboniferous, most of Svalbard developed into a carbonate platform with episodes of evaporite formation. These conditions lasted through the Early Permian, while the later part of the Permian experienced renewed clastic influx and a subsequent hiatus at the era boundary (Steel & Worsley 1984). Late-Palaeozoic sedimentation in the Svalbard/Barents Sea area was continuous with that in the Wandel Sea Basin in northeastern Greenland (Håkansson & Stemmerik 1984), a site at that time situated not farther than maybe 100 km from what is now the western coast of Svalbard.

1.4.5 Mesozoic

The Mesozoic stratigraphic record consists of repeated clastic sedimentary successions, mainly delta-related coastal and shallow shelf sediments (Triassic-Early Jurassic), deeper shelf sediments (Middle Jurassic to earliest Cretaceous) and again shallow shelf/delta deposits (later part of Early Cretaceous). The source area of the sediments was mainly situated in the west, and later also in the north, while the basin opened towards the present Barents Sea (Steel & Worsley 1984). This view is consistent with the less complete Mesozoic sections in the Wandel Sea Basin of NE Greenland (Håkansson et al. 1991). Early Jurassic block faulting and development of sedimentary basins during the Cretaceous in the Wandel Sea Basin are explained by the Mesozoic onset of transform faulting between Greenland and the Barents Sea (Birkelund & Håkansson 1983; Håkansson et al. 1991). In Svalbard, no such tectonics are seen, and the entire Upper Cretaceous is lacking due to an overall uplift, with highest uplift rates in the northwest.
The first sign of break-up between Greenland and Europe and the opening of the Arctic and North Atlantic oceans recorded in Svalbard is the intrusion of dolerites from the latest Jurassic through the Early Cretaceous (Burov et al. 1977). They occur most commonly as sills in Carboniferous through to Jurassic strata (progressively younger to the east). On Kong Karls Land, in eastern Svalbard, basaltic lavas were extruded during the later part of the Early Cretaceous. They belong to a larger volcanic province which also includes large parts of the Barents Sea and Franz Joseph Land.

1.4.6 Cenozoic

The opening of the Arctic and North Atlantic oceans caused a tectonic overprint with convergent structures in the Paleocene and Eocene. Structures that developed were related to a transform fault system, the Spitsbergen Fracture Zone, or “De Geer Fault”, situated offshore to the west of Svalbard (Fig. 1-02). Convergent movements during part of the transform movement caused the reverse uplift of the western basement province, thrusting the basement rocks and overlying cover strata onto the simultaneously developing foreland basin, the Central Cenozoic Basin (Steel et al. 1985). Though associated with a major, dextral plate transform setting between the Greenland and Barents shelves and previously described as a typical transpressive orogen (Harland 1969; Harland & Horsfield 1974; Lowell 1972), the Cenozoic fold-thrust belt consists mainly of convergent structures (e.g. Maher et al. 1986; Nøttvedt et al. 1988; Dallmann & Maher 1989; Haremo et al. 1990; Bergh & Andresen 1990). This led to a decoupling model (Nøttvedt et al. 1988; Maher & Craddock 1988), meaning that strike-slip and convergent movements may be localised in different deformation zones. Recent work revealed the local existence of additional strike-slip-related structures along several N-S oriented fault zones (Dallmann 1992; McCann & Dallmann 1996; Maher et al. 1997).
ENE-WSW shortening was transferred east ahead of the fold belt along high level detachments within the cover sediments, and interfered with renewed, reverse faulting along basement-involved structures farther east (Billefjorden and Lomfjorden faultzones; Haremo et al. 1990; Haremo & Andresen 1992; Haremo et al. 1993; Miloslavskij et al. 1993).
During later stages of foldbelt development (Eocene-Oligocene), minor sedimentary basins (especially the Forlandsundet Basin) developed in westernmost areas. Their structural record is complex and difficult to relate to the deformation phases of the main foldbelt (Gabrielsen et al. 1992, Kleinspehn & Teyssier 1992). The latest tectonic overprint was an overall E-W extension that affected more or less all favourably oriented earlier faults and generated new faults in the foldbelt area. These fault movements must be seen in the context of the post-Eocene development of a passive continental margin to the west, when Svalbard, drifting along the transform fault system, had separated from the continental shelf of Greenland.

1.4.7 Cenozoic and Quaternary volcanic activity

Volcanic activity of both Cenozoic and Quaternary age occurred in NW Spitsbergen, overlying Devonian and Precambrian rocks. The Cenozoic volcanites are plateau basalts (transitional olivine basalts) of mainly Miocene to Pliocene age (Burov & Zagruzina 1976; Prestvik 1978), while the Quaternary volcanites are volcanic centres (off-ridge alkali basalts) situated on faults that date back at least to the Devonian; their age is probably between 100,000 and 250,000 years (Skjelkvåle et al. 1989). Hot springs in several places in northwestern and southern Spitsbergen witness to continuously high geothermal gradients along the Cenozoic foldthrust belt.

Fig. 1-03
Fig. 1-03: Table of post-Caledonian tectonic events and character of sedimentation in Svalbard. The absolute age scale refers to Haq & van Eysinga (1987).Fig. 1-04
Fig. 1-04: Geological overview map of Svalbard showing lithostratigraphic groups. Legend for symbols used on all maps.Fig. 1-05
Fig. 1-05: Overview map of Svalbard showing major structural elements. Legend for symbols used on all maps.Fig. 1-06
Fig. 1-06: Map of Svalbard showing names of major geographical features and an index of detailed maps.

 

Geology of Saudi Arab

Saudi Arabia is situated in the southern part of the Arabian plate, one of the youngest of the 10 or more plates that make up the present-day surface of the Earth. In this area, the plate comprises a crystalline basement of Precambrian continental crust about 40-45 km thick and mostly 870-550 million years old, an overlying sequence of younger Phanerozoic sedimentary rocks that range in age from Cambrian (540 Ma) to the Pleistocene and in thickness from zero to 10 km, surficial Cenozoic flood basalt, and Paleogene-Holocene intracontinental and, now, oceanic basins along the Red Sea and Gulf of Aden

Prior to the opening and uplift of the rifted margins of the Red Sea and Gulf of Aden, Phanerozoic rocks covered and concealed the basement rocks, but erosion and unroofing since then exposes them as the Arabian Shield, in the west, and in minor outcrops elsewhere. The Precambrian includes terranes of volcanic, sedimentary, and calc-alkaline intrusive rocks that form a collage of strongly deformed magmatic arcs, other types of less deformed volcanic and sedimentary rocks that constitute overlap assemblages deposited in sag and rift basins, bodies of gneiss that reflect local uplift, and large amounts of late- to posttectonic granitoids that result from the development of voluminous, post-orogeny anatextic magma. The Precambrian terranes converged and amalgamated between 780-650 Ma during orogenic events that involved deformation, metamorphism, and uplift, culminating in the Nabitah orogeny, and were partly covered by overlap assemblages and intruded by plutonic rocks during a subsequent 100 million-year period of orogenic collapse, extension, exhumation, and strike-slip faulting.

The Phanerozoic rocks are unconformable on the Precambrian, and mostly little deformed, affected by open folds and block faulting in the Arabian Platform (east and north of the exposed shield) and in the Red Sea and Gulf of Aden basins. The rocks in the Arabian Platform accumulated on a stable marine-to-fluviatile shelf. Uplift and collapse of arches and basins, movements on fault blocks, and the migrating of shorelines back and forward across this shelf resulted in the intercalations and facies migrations of sandstones, siltstones, carbonates, and evaporites (salt basins) that characterize the Phanerozoic of this region. The Cenozoic sedimentary, evaporitic, and minor volcanic rocks that fill the Red Sea basin were deposited in an initial intracontinental rift that evolved, with ongoing spreading, into the present-day narrow marine basin.

The separation of Arabian and Africa, which began about 25 million years ago, entailed rifting and sea-floor spreading along the axes of the Red Sea and Gulf of Aden and the northward drift of the Arabian Plate and eventual collision with Eurasia. During this period, in addition to the formation of new oceanic crust and sedimentation in the Red Sea and Gulf of Aden basins, the western and southern margins of the Arabian Plate were uplifted and partly covered by subaerial flood basalt, resulting in the creation of the Red Sea Escarpment and fields of lava (harrat), and the northern and northeastern margins were sutured to rocks in Iran and Turkey, causing crustal shortening and the formation of the Zagros fold-and-thrust belt.

The rocks of Saudi Arabia range in age from the Precambrian to the present day, forming part of a larger unit that includes the Arabian Peninsula and is known as the Arabian Plate. Some Precambrian rocks in this region date back to the Archean (nearly 3 million years ago) but most are Neoproterozoic (1000-540 Ma*). They originated as volcanic islands or as chains of volcanoes along spreading centers and subduction zones in a Neoproterozoic ocean and against ancient continental margins, and were folded and uplifted toward the end of the Precambrian as a large belt of mountains. The mountains existed between about 680-540 Ma and were part of one of the largest mountain belts ever known to have existed on Earth. By the end of the Precambrian, the mountains had been eroded and only their roots are preserved, exposed in western Saudi Arabia in the Arabian shield.

The younger rocks in Saudi Arabia belong to the Paleozoic (540-250 Ma), Mesozoic (250-65 Ma), and Cenozoic (65 Ma to Recent) (collectively referred to as Phanerozoic cover), and crop out as relatively flat lying beds of sedimentary rocks such as sandstone, siltstone, limestone, and evaporites (salt deposits), and volcanic rocks. The rocks were deposited unconformably on the underlying Precambrian basement, in riverbeds, in glacial valleys, and in shallow seas, or were extruded from subaerial volcanoes. The rocks north and east of the Arabian shield are referred to as the Arabian Platform; those on the shield are mainly harrat (fields of Cenozoic flood basalt); and those west of the shield are Cenozoic rocks that occupy the Red Sea basin. The youngest deposits in the region include coral limestone and unconsolidated sand, silt, gravel, and sabkhah, which accumulated in the sand seas of Ar Rub al Khali and An Nafud, filled dried-up lake beds and wadis, and fringed the coastlines.

The Precambrian contain most of Saudi Arabia’s known metal deposits of gold, silver, copper, zinc, iron, and magnesium. The Phanerozoic cover contains the oil resources and deposits of bauxite (the source of aluminum), phosphate, clay, limestone, silica sand, and lightweight aggregate that are of increasing importance to the industrial development of the Kingdom.

Geology

Early History of the Earth
The earth and the rest of the solar system were formed about 4.57 billion years ago from an enormous cloud of fragments of both icy and rocky material which was produced from the explosions (super novae) of one or more large stars It is likely that the proportions of elements in this material were generally similar to those shown in the diagram below. Although most of the cloud was made of hydrogen and helium, the material that accumulated to form the earth also included a significant amount of the heavier elements, especially elements like carbon, oxygen, iron, aluminum, magnesium and silicon. As the cloud started to contract, most of the mass accumulated towards the center to become the sun. Once a critical mass had been reached the sun started to heat up through nuclear fusion of hydrogen into helium. In the region relatively close to the sun – within the orbit of what is now Mars – the heat was sufficient for most of the lighter elements to evaporate, and these were driven outward by the solar wind to the area of the orbits of Jupiter and the other gaseous planets. As a result, the four inner planets – Mercury, Venus, Earth and Mars are “rocky” in their composition, while the four major outer planets, Jupiter, Saturn, Neptune and Uranus are “gaseous”.
As the ball of fragments and dust that was to eventually become the earth grew, it began to heat up – firstly from the heat of colliding particles – but more importantly from the heat generated by radioactive decay (fission) of uranium, thorium, and potassium (figure below). Within a few hundred million years the temperature probably rose to several thousand degrees, hot enough to melt most things. This allowed the materials to be sorted out so that the heavier substances sank towards the center, and the lighter substances floated towards the surface.

Capture

To begin with, much of the iron and magnesium would have combined with silicon and oxygen to form heavy silicate minerals such as olivine: (Mg,Fe)2SiO4 and pyroxene (Mg,Fe)SiO3. Most of the remaining iron (along with some nickel and sulphur) would have migrated towards the center – forming a very heavy metallic core. Meanwhile, much of the aluminum, sodium and potassium would have combined with oxygen and silicon to form minerals such as quartz (SiO2)and feldspar (NaAlSi3O8) that would have floated towards the surface to form the crust (see figure below). We will look more closely at the characteristics of the core, mantle and crust later on. The original material that formed the earth included some hydrogen, oxygen, carbon and nitrogen, and these would have been brought to the surface during volcanic eruptions as molecules such as water, carbon dioxide, methane and nitrogen gas. By around 4 billion years (b.y.) ago it is likely that the earth had an atmosphere rich in carbon dioxide and nitrogen along with lots of water vapor. Initially the earth’s surface and atmosphere were probably too hot for the water to come down as rain, but as the crust cooled and hardened it kept most of the earth’s internal heat inside, and eventually the atmosphere cooled enough for rain to fall and create bodies of water on the surface.

These conceptual topics of General Geology To assist you learn more as self study, here some outlines

How does physical geology differ
from historical geology?
What is the fundamental didifference
between uniformitarianism and
catastrophism?
What is relative dating? What are
some principles of relative dating?
How does a scientific hypothesis
differ from a scientific theory?
What are Earth’s four major
“spheres”?
Why can Earth be regarded as a
system?
What is the rock cycle? Which geologic interrelationships are illustrated by the cycle?
How did Earth and the other planets in our solar system originate?
What criteria were used to establish
Earth’s layered structure?
What are the major features of the
continents and ocean basins?
What is the theory of plate tectonics? How do the three types of
plate boundaries differ?

The Science of Geology

The subject of this text is geology, from the Greek geo, “Earth,” and logos, “discourse.”
It is the science that pursues an understanding of planet Earth. Geology is traditionally divided into two broad
areas—physical and historical. Physical geology examines the materials composing Earth and seeks to understand the many
processes that operate beneath and upon its surface (Figure 1.1). The aim of historical geology, on the other hand, is to
understand the origin of Earth and its development through time. Thus, it strives to establish a chronological arrangement of the multitude of physical and biological changes that have occurred in the geologic past. The study of physical geology logically precedes the study of Earth history because we must first understand how Earth works before we attempt to unravel its past. It should also be pointed out that physical and historical geology are divided into many areas of specialization. Table 1.1 provides a partial list. . table To understand Earth is challenging because our planet is a dynamic body with many interacting parts and a complex history. Throughout its long existence, Earth has been changing. In fact, it is changing as you read this page and will continue to do so into the foreseeable future. Sometimes the changes are rapid and violent, as when landslides or volcanic eruptions occur. Just as often, change takes place so slowly that it goes unnoticed during a lifetime. Scales of size and space also vary greatly among the phenomena that geologists study. Sometimes they must focus on phenomena that are submicroscopic, and at other times they must deal with features that are continental or global in scale. Geology is perceived as a science that is done in the out of doors, and rightly so. A great deal of geology is based on measurements, observations, and experiments conducted in the field. But geology is also done in the laboratory where, for example, the study of various Earth materials provides insights into many basic processes. Moreover, the development of sophisticated computer models allows for the simulation of many of our planet’s complex systems. Frequently, geology requires an understanding and application of knowledge and principles from physics, chemistry, and biology. Geology is a science that seeks to expand our knowledge of the natural world and our place in it.

Catastrophism

During the seventeenth and eighteenth centuries the doctrine of catastrophism strongly influenced people’s thinking about Earth. Briefly stated,catastrophists believed that Earth’s landscapes had been shaped primarily by great catastrophes. Features such as mountains and canyons, which today we know take great periods of time to form, were explained as having been produced by sudden and often worldwide disasters produced by unknown causes that no longer operate. This philosophy was an attempt to fit the rates of Earth processes to the then current ideas on the age of Earth.The Pakistan flooding, July–November 2010 (DFO event 3696) caused close to 2000 fatalities, displaced 20,000,000 inhabitants for weeks to many months, and was 7.5 on a duration–area affected–intensity scale that compares flood magnitudes on a global basis (Chorynski et al., 2012; Brakenridge, 2012). Flooding along the Indus River began in mid- to late-July following unusually heavy monsoonal rain in northern Pakistan and was sustained in downstream areas through the end of 2010. Exceptional damage was inflicted on crops and cropland and on agriculture support systems such as canals and levees; 4,500,000 mainly agricultural workers lost their employment for 2010–2011 (Khan, 2011).

The Birth of Modern Geology

Against this backdrop of Aristotle’s views and Earth created in 4004 B.C., a Scottish physician the and gentleman farmer named James Hutton published Theory of the Earth in 1795. In this work Hutton put forth a fundamental principle that is a pillar of geology today: uniformitarianism. It states that the physical, chemical, and biological laws that operate today also operated in the geologic past.In other words, the forces and processes that we observe shaping our planet today have been at work for a very long time. Thus, to understand ancient rocks, we must first understand present-day processes and their results. This idea is commonly stated as the present is the key to the past. Prior to Hutton’s Theory of the Earth, no one had effectively demonstrated that geological processes can continue over extremely long periods of time. Hutton persuasively argued that forces that appear small could, over long spans of time, produce effects just as great as those resulting from sudden catastrophic events. Hutton carefully cited verifiable observations to support his ideas. For example, when he argued that mountains are sculpted and ultimately destroyed by weathering and the work of running water, and that their wastes are carried to the oceans by processes that can be observed, Hutton said “We have a
chain of facts which clearly demonstrates . . . that the materials of the wasted mountains have traveled through the rivers”; and further, “There is not one step in all this progress . . . that is not to be actually perceived.” He then went on to summarize this thought by asking a question and immediately providing the answer: “What more can we require? Nothing but time.”

Geologic Time

Exploring this series of exhibits will take you on a journey through the history of the Earth, with stops at particular points in time to examine the fossil record and stratigraphy. Although Hutton and others recognized that geologic time is exceedingly long, they had no methods to accurately determine the age of Earth. However, in 1896 radioactivity was discovered. Using radioactivity for dating was first attempted in 1905 and has been refined ever since. Geologists are now able to assign fairly accurate dates to events in Earth history.For example, we know that the dinosaurs died out about 65 million years ago. Today the age of Earth is put at about 4.5 billion years. The concept of geologic time is new to many non geologists. People are accustomed to dealing with increments of time that are measured in hours, days, weeks, and years. Our history books often examine events over spans of centuries, but even a century is difficult to appreciate fully. For most of us, someone or something that is 90 years old is very old, and a 1000-year-old artifact is ancient.

Fossils, the remains or traces of prehistoric life, were also essential to the development of a geologic time scale. Fossils are the basis for the principle of fossil succession, which states that fossil organisms succeed one another in a definite and determinable order, and therefore any time period can be recognized by its fossil content. This principle was laboriously worked out over decades by collecting fossils from countless rock layers around the world. Once established, it allowed geologists to identify rocks of the same age in widely separated places and to build the geologic time scale shown in Figure 1.9.Capture Notice that units having the same designations do not necessarily extend for the same number of years. For example, the Cambrian period lasted about 56 million years, whereas the Silurian period spanned only about 28 million years. This situation exists because the basis for establishing the time scale was not the regular rhythm of a clock, but the changing character of life forms through time. Specific dates were added long after the time scale was established. A glance at Figure 1.9 also reveals that the Phanerozoic eon is divided into many more units  than earlier eons even though it encompasses only about 12 percent of Earth history. The meager fossil record for these earlier eons is the primary reason for the lack of detail on this portion of the time scale. Without abundant fossils, geologists lose a very important tool for subdividing geologic time.

Earth’s Spharer

A view such as the one in Figure 1.13A provided the Apollo 8 astronauts as well as the rest of humanity with a unique perspective of our home. Seen from space, Earth is breathtaking in its beauty and startling in its solitude. Such an image reminds us that our home is, after all, a planet—small, self-contained, and in some ways even fragile. As we look more closely at our planet from space, it becomes apparent that Earth is much more than rock and soil. In fact, the most conspicuous features in Figure 1.13A are not continents but swirling clouds suspended above the surface and the vast global ocean. These features emphasize the importance of water to our planet.

Capture

The closer view of Earth from space shown in Figure 1.13B helps us appreciate why the physical environment is traditionally divided into three major parts: the water portion of our planet, the hydrosphere; Earth’s gaseous envelope, the atmosphere; and, of course, the solid Earth, or geosphere. It needs to be emphasized that our environment is highly integrated and is not dominated by rock, water, or ESSENTIALS OF GEOLOGY A. B. air alone. Rather, it is characterized by continuous interactions as air comes in contact with rock, rock with water, and water with air. Moreover, the biosphere, which is the totality of all plant and animal life on our planet, interacts with each of the three physical realms and is an equally integral part of the planet. Thus, Earth can be thought of as consisting of four major spheres: the hydrosphere, atmosphere, geosphere, and biosphere. The interactions among Earth’s four spheres are incalculable. Figure 1.14 provides us with one easy-to-visualize example. The shoreline is an obvious meeting place for rock, water, and air. In this scene, ocean waves that were created by the drag of air moving across the water are breaking against the rocky shore. The force of the water can be powerful, and the erosional work that is accomplished can be great.

Hydrosphere
Earth is sometimes called the blue planet. Water more than anything else makes Earth unique. The hydrosphere is a dynamic mass of liquid that is continually on the move, evaporating from the oceans to the atmosphere, precipitating back to the land, and running back to the ocean again. The global ocean is certainly the most prominent feature of the hydrosphere, blanketing nearly 71 percent of Earth’s surface to an average depth of about 3800 meters (12,500 feet). It accounts for about 97 percent of Earth’s water. However, the hydrosphere also includes the freshwater found underground and in streams, lakes, and glaciers. Moreover, water is an important component of all living things. Although these latter sources constitute just a tiny fraction of the total, they are much more important than their meager percentage indicates. Streams, glaciers, and groundwater are responsible for creating many of our planet’s varied land forms, as well as the fresh water that is so vital to life on land.Capture

Atmosphere
Earth is surrounded by a life-giving gaseous envelope called the atmosphere. When we watch a high-flying jet plane cross the sky, it seems that the atmosphere extends upward for a great distance (Figure 1.15). However, when compared to the thickness (radius) of the solid Earth (about 6400 kilometers or 4000 miles), the atmosphere is a very shallow layer. One-half lies below an altitude of 5.6 kilometers (3.5 miles), and 90 percent occurs within just 16 kilometers (10 miles) of Earth’s surface. Despite its modest dimensions, this thin blanket of air is an integral part of the planet. It not only provides the air that we breathe but also acts to protect us from the Sun’s intense heat and dangerous ultraviolet radiation. The energy exchanges that continually occur between the atmosphere and the surface and between the atmosphere and space produce the effects we call weather and climate.

Biosphere
The biosphere includes all life on Earth. Ocean life is concentrated in the sunlit surface waters of the sea. Most life on land is also concentrated near the surface, with tree roots and burrowing animals reaching a few meters underground and flying insects and birds reaching a kilometer or so above Earth. A surprising variety of life forms are also adapted to extreme environments. For example, on the ocean floor where pressures are extreme and no light penetrates, there are places where vents spew hot, mineral-rich fluids that support communities of exotic life forms(Figure 1.16). Capture On land, some bacteria thrive in rocks as deep as 4 kilometers (2.5 miles) and in boiling hot springs. Moreover, air currents can carry microorganisms many kilometers into the atmosphere. But even when we consider these extremes, life still must be thought of as being confined to a narrow band very near Earth’s surface. Plants and animals depend on the physical environment for the basics of life. However, organisms do not just respond to their physical environment. Indeed, the biosphere powerfully influences the other three spheres. Without life, the makeup and nature of the geosphere, hydrosphere, and atmosphere would be very different.

Geosphere

Lying beneath the atmosphere and the oceans is the solid Earth, or geosphere. The geosphere extends from the surface to the center of the planet, a depth of 6400 kilometers, making it by far the largest of Earth’s four spheres. Much of our study of the solid Earth focuses on the more accessible surface features. Fortunately, many of these features represent the outward
expressions of the dynamic behavior of Earth’s interior. By examining the most prominent surface features and their global extent, we can obtain clues to the dynamic processes that have shaped our planet. A first look at the structure of Earth’s interior and at the major surface features of the geosphere will come later in the chapter. Soil, the thin veneer of material at Earth’s surface that supports the growth of plants, may be thought of as part of all four spheres. The solid portion is a mixture of weathered rock debris (geosphere) and organic matter from decayed plant and animal life (biosphere). The decomposed and disintegrated rock debris is the product of weathering processes that require air (atmosphere) and water (hydrosphere). Air and water also occupy the open spaces between the solid  particles.  Anyone who studies Earth soon learns that our planet is a dynamic body with many separate but interacting parts or spheres.The hydrosphere, atmosphere, biosphere, and geosphere and all of their components can be studied separately. However, the parts are not isolated. Each is related in some way to the others to produce a complex and continuously interacting whole that we call the Earth system.

WHAT IS A SYSTEM?

Most of us hear and use the term system frequently. We may service our car’s cooling system, make use of the city’s transportation system, and participate in the political system.A news report might inform us of an approaching weather system.Further, we know that Earth is just a small part of a larger system known as the solar system which in turn is a subsystem of the even larger system called the Milky Way Galaxy. Loosely defined, a system can be any size group of interacting parts that form a complex whole. Most natural systems are driven by sources of energy that move matter and/or energy from one place to another. A simple analogy is a car’s cooling system, which contains a liquid (usually water and antifreeze) that is driven from the engine to the radiator and back again. The role of this system is to transfer heat generated by combustion in the engine to the radiator, where moving air removes it from the system. Hence, the term cooling system.

Earth System Science
A simple example of the interactions among different parts of the Earth system occurs every winter as moisture evaporates from the Pacific Ocean and subsequently falls as rain in the hills of southern California, triggering destructive landslides. A case study in Chapter 8 explores such an event (see p. 189). The processes that move water from the hydrosphere to the atmosphere and then to the solid Earth have a profound impact on the plants and animals (including humans) that inhabit the affected regions. Figure 1.17 Capture provides another example. Scientists have recognized that to more fully understand our planet, they must learn how its individual components (land, water, air, and life forms) are interconnected. This endeavor, called Earth system science, aims to study Earth as a system composed of numerous interacting parts, or subsystems.Rather than looking through the limited lens of only one of the traditional sciences—geology, atmospheric science, chemistry, biology, and so forth—Earth system science attempts to integrate the knowledge of several academic fields.
Using this interdisciplinary approach, we hope to achieve the level of understanding necessary to comprehend and solve many of our global environmental problems. Scientists have determined that since 1906 global average surface temperature has increased by about 0.7°C (1.3°F). By the end of the twenty-first century, globally averaged surface temperature is projected to increase by an additional 1.7 to 3.9°C (3 to 7°F).

ENERGY FOR THE EARTH SYSTEM. The Earth system is powered by energy from two sources. The Sun drives external processes that occur in the atmosphere, hydrosphere, and at Earth’s surface. Weather and climate, ocean circulation, and erosional processes are driven by energy from the Sun. Earth’s interior is the second source of energy. Heat remaining from when our planet formed, and heat that is continuously generated by decay of radioactive elements, power the internal processes that produce volcanoes, earthquakes, and mountains.

CYCLES IN THE EARTH SYSTEM. A more familiar loop or subsystem is the hydrologic cycle.It represents the unending circulation of Earth’s water among the hydrosphere, atmosphere, biosphere, and geosphere. Water enters the atmosphere by evaporation from Earth’s surface and by transpiration from plants. Water vapor condenses in the atmosphere to form clouds, which in turn produce precipitation that falls back to Earth’s surface. Some of the rain that falls onto the land sinks in to be taken up by plants or become groundwater, and some flows across the surface toward the ocean.

Before going ahead with Rock Cycle we should know What is Rocks?

The study of geology is the study of the Earth, and so is ultimately the study of rocks. Geologists define a rock as:A bound aggregate of minerals, mineraloids, or fragments of other rocks.

The use of the word ‘bound’ means that a rock must have structural integrity, e.g. an aggregate of sand does not become a rock until the grains are bound together. Typical binding agents are very fine grained minerals (e.g. calcite, clay) or mineraloids (e.g. chert, glass), though in some rock types the crystals are inter-grown and no binder is required.

There are three major groups of rocks:

  1. Igneous rocks are those that have formed by the cooling and crystallisation of magma, either at the Earth’s surface or within the crust;
  2. Sedimentary rocks are those that have formed when eroded particles of other rocks have been deposited (on the ocean floor, stream/lake beds, etc) and compacted, or by the precipitation of minerals / mineraloids from water;
  3. Metamorphic rocks are those that have formed when existing rocks have undergone pressure and / or temperature changes so that their original mineralogy has been changed.

Each of these rock groups contains many different types of rock, and each can be identified from its physical features.

Being able to describe and name rocks is one of the fundamental skills of a geologist. Important information regarding the nature of rocks is communicated through concise, accurate descriptions. This information allows the geologist to identify the rock, and, in the process, to learn about its history and the geological environment in which it was formed.

A knowledge of field relationships between different rock units is fundamental to the study of rocks. It is gained from mapping and observing rocks in the field. In depth analysis of rocks using a microscope or sophisticated analytical laboratory equipment provides important information on their composition. In between these extremes is the observation and description of hand specimens. The term hand specimen refers to an easily manageable piece of rock that can be picked up and easily transported back to the geologist’s base for further investigation.

The Rock Cycle:
One of Earth’s Subsystems

Rock is the most common and abundant material on Earth. To a curious traveler, the variety seems nearly endless. When a rock is examined closely, we find that it consists of smaller crystals or grains called minerals. Minerals are chemical compounds (or sometimes single elements), each with its own composition and physical properties. The grains or crystals may be microscopically small or easily seen with the unaided eye. The nature and appearance of a rock is strongly influenced by the minerals that compose it. In addition, a rock’s texture—the size, shape, and/or arrangement of its constituent minerals—also has a significant effect on its appearance. A rock’s mineral composition and texture, in turn, are a reflection of the geologic processes that created it (Figure 1.20). Capture The characteristics of the rocks in Figure 1.21 provided geologists with the clues they needed to determine the processes that formed them. This is true of all rocks. Such analyses are critical to an understanding of our planet. This understanding has many practical applications, as in the search for basic mineral and energy resources and the solution of environmental problems.

This means that our planet consists of many interacting parts that form a complex whole. Nowhere is this idea better illustrated than when we examine the rock cycle (Figure 1.22). The rock cycle allows us to view many of the interrelationships among different parts of the Earth system. Knowledge of the rock cycle will help you more clearly understand the idea that each rock group is linked to the others by the processes that act upon and within the planet. You can consider the rock cycle to be a simplified but useful overview of physical geology.

Capture

Alternative Paths
The paths shown in the basic cycle are not the only ones that are possible. To the contrary, other paths are just as likely to be followed as those described in the preceding section. These alternatives are indicated by the blue arrows in Figure 1.22.
Igneous rocks, rather than being exposed to weathering and erosion at Earth’s surface, may remain deeply buried. Eventually these masses may be subjected to the strong compressional forces and high temperatures associated with mountain building. When this occurs, they are transformed directly into metamorphic rocks. Metamorphic and sedimentary rocks, as well as sediment, do not always remain buried. Rather, overlying layers may be stripped away, exposing the once buried rock. When this happens, the material is attacked by weathering processes and turned into new raw materials for sedimentary rocks. Where does the energy that drives Earth’s rock cycle come from? Processes driven by heat from Earth’s interior are responsible for forming igneous and metamorphic rocks. Weathering and the movement of weathered material are external processes powered by energy from the Sun. External processes produce sedimentary rocks.