Misplaced Pages

#675324

78-895: The Iranian plateau or Persian plateau is a geological feature spanning parts of the Caucasus , Central Asia , South Asia , and West Asia . It makes up part of the Eurasian Plate , and is wedged between the Arabian Plate and the Indian Plate . The plateau is situated between the Zagros Mountains to the west, the Caspian Sea and the Köpet Dag to the north, the Armenian Highlands and

156-535: A characteristic fabric . All three types may melt again, and when this happens, new magma is formed, from which an igneous rock may once again solidify. Organic matter, such as coal, bitumen, oil, and natural gas, is linked mainly to organic-rich sedimentary rocks. To study all three types of rock, geologists evaluate the minerals of which they are composed and their other physical properties, such as texture and fabric . Geologists also study unlithified materials (referred to as superficial deposits ) that lie above

234-485: A petrographic microscope , where the minerals can be identified through their different properties in plane-polarized and cross-polarized light, including their birefringence , pleochroism , twinning , and interference properties with a conoscopic lens . In the electron microprobe, individual locations are analyzed for their exact chemical compositions and variation in composition within individual crystals. Stable and radioactive isotope studies provide insight into

312-569: A plateau , it is far from flat, and contains several mountain ranges; its highest point is Noshaq in the Hindu Kush at 7,492 metres (24,580 ft), and its lowest point is the Lut Desert to the east of Kerman , Iran, at below 300 metres (980 ft). In geology, the plateau region of Iran primarily formed from the accretionary Gondwanan terranes between the Turan platform to

390-579: A bird research and education center was established by KuzeyDoğa , a Turkish non-governmental organization for nature conservation, in the Aras Valley at the village Yukarı Çıyrıklı, in the Tuzluca district of Iğdır Province , Turkey. It is one of Turkey's two bird-ringing stations that remain active yearly. Between 2006 and 2021, more than 145,000 birds of 201 species were ringed, and 306 bird species were observed at this station. Sixty-three percent of

468-577: A geographic political boundary. Under the terms of the Treaty of Gulistan and the Treaty of Turkmenchay , the river was chosen as the border limit between the Russian Empire and Qajar Iran , as the latter was forced to cede its Caucasian territories to Russia. Because of these 19th-century border changes, one modern, not widely accepted scheme draws Aras River as the line of continental demarcation between Europe and Asia. In 1963–1970, Iran and

546-627: A length of less than a meter. Rocks at the depth to be ductilely stretched are often also metamorphosed. These stretched rocks can also pinch into lenses, known as boudins , after the French word for "sausage" because of their visual similarity. Where rock units slide past one another, strike-slip faults develop in shallow regions, and become shear zones at deeper depths where the rocks deform ductilely. The addition of new rock units, both depositionally and intrusively, often occurs during deformation. Faulting and other deformational processes result in

624-452: A means to provide information about geological history and the timing of geological events. The principle of uniformitarianism states that the geological processes observed in operation that modify the Earth's crust at present have worked in much the same way over geological time. A fundamental principle of geology advanced by the 18th-century Scottish physician and geologist James Hutton

702-608: A number of fields, laboratory, and numerical modeling methods to decipher Earth history and to understand the processes that occur on and inside the Earth. In typical geological investigations, geologists use primary information related to petrology (the study of rocks), stratigraphy (the study of sedimentary layers), and structural geology (the study of positions of rock units and their deformation). In many cases, geologists also study modern soils, rivers , landscapes , and glaciers ; investigate past and current life and biogeochemical pathways, and use geophysical methods to investigate

780-499: A single environment and do not necessarily occur in a single order. The Hawaiian Islands , for example, consist almost entirely of layered basaltic lava flows. The sedimentary sequences of the mid-continental United States and the Grand Canyon in the southwestern United States contain almost-undeformed stacks of sedimentary rocks that have remained in place since Cambrian time. Other areas are much more geologically complex. In

858-400: A variety of applications. Dating of lava and volcanic ash layers found within a stratigraphic sequence can provide absolute age data for sedimentary rock units that do not contain radioactive isotopes and calibrate relative dating techniques. These methods can also be used to determine ages of pluton emplacement. Thermochemical techniques can be used to determine temperature profiles within

SECTION 10

#1732757450676

936-462: Is Arax or Araks ( Armenian : Արաքս ). Historically, it was called Eraskh ( Old Armenian : Երասխ , Yeraskh in modern pronunciation) by Armenians and its Old Georgian name is Rakhsi ( რახსი ). In Azerbaijani , the river's name is Araz . In Persian , Kurdish and Turkish its name is ارس ( Aras ). The Aras is supported by the Kocagün stream, Dallı stream and Orman stream from

1014-655: Is a major academic discipline , and it is central to geological engineering and plays an important role in geotechnical engineering . The majority of geological data comes from research on solid Earth materials. Meteorites and other extraterrestrial natural materials are also studied by geological methods. Minerals are naturally occurring elements and compounds with a definite homogeneous chemical composition and an ordered atomic arrangement. Each mineral has distinct physical properties, and there are many tests to determine each of them. Minerals are often identified through these tests. The specimens can be tested for: A rock

1092-506: Is a point along the Aras at an elevation of 380 metres (1,250 ft). The following rivers are tributaries of the Aras, from source to mouth: In Armenian tradition, the river is named after Arast , a great-grandson of the legendary Armenian patriarch Haik . The name was later Hellenized to Araxes and was applied to the Kura–Araxes culture , a prehistoric people who flourished in

1170-422: Is accomplished in two primary ways: through faulting and folding . In the shallow crust, where brittle deformation can occur, thrust faults form, which causes the deeper rock to move on top of the shallower rock. Because deeper rock is often older, as noted by the principle of superposition , this can result in older rocks moving on top of younger ones. Movement along faults can result in folding, either because

1248-556: Is an igneous rock . This rock can be weathered and eroded , then redeposited and lithified into a sedimentary rock. Sedimentary rocks are mainly divided into four categories: sandstone, shale, carbonate, and evaporite. This group of classifications focuses partly on the size of sedimentary particles (sandstone and shale), and partly on mineralogy and formation processes (carbonation and evaporation). Igneous and sedimentary rocks can then be turned into metamorphic rocks by heat and pressure that change its mineral content, resulting in

1326-460: Is an intimate coupling between the movement of the plates on the surface and the convection of the mantle (that is, the heat transfer caused by the slow movement of ductile mantle rock). Thus, oceanic parts of plates and the adjoining mantle convection currents always move in the same direction – because the oceanic lithosphere is actually the rigid upper thermal boundary layer of the convecting mantle. This coupling between rigid plates moving on

1404-469: Is any naturally occurring solid mass or aggregate of minerals or mineraloids . Most research in geology is associated with the study of rocks, as they provide the primary record of the majority of the geological history of the Earth. There are three major types of rock: igneous , sedimentary , and metamorphic . The rock cycle illustrates the relationships among them (see diagram). When a rock solidifies or crystallizes from melt ( magma or lava ), it

1482-531: Is fed mainly to horses . Sesame is grown and made into sesame oil . Mushrooms and manna were also seen in the plateau area as of 1920. Caraway is grown in the Kerman Province . Geology Geology describes the structure of the Earth on and beneath its surface and the processes that have shaped that structure. Geologists study the mineralogical composition of rocks in order to get insight into their history of formation. Geology determines

1560-433: Is horizontal). The principle of superposition states that a sedimentary rock layer in a tectonically undisturbed sequence is younger than the one beneath it and older than the one above it. Logically a younger layer cannot slip beneath a layer previously deposited. This principle allows sedimentary layers to be viewed as a form of the vertical timeline, a partial or complete record of the time elapsed from deposition of

1638-484: Is primarily accomplished through normal faulting and through the ductile stretching and thinning. Normal faults drop rock units that are higher below those that are lower. This typically results in younger units ending up below older units. Stretching of units can result in their thinning. In fact, at one location within the Maria Fold and Thrust Belt , the entire sedimentary sequence of the Grand Canyon appears over

SECTION 20

#1732757450676

1716-663: Is situated in the mountains at an elevation of 1,546 meters (5,072 ft). The headwaters of major rivers arise in the Anti-Taurus: the east-flowing Aras River flows into the Caspian Sea , and the south-flowing Euphrates and Tigris join in Iraq before flowing into the Persian Gulf . Several small streams that flow into the Black Sea or landlocked Lake Van also originate in these mountains. The Indus River begins in

1794-568: Is that "the present is the key to the past." In Hutton's words: "the past history of our globe must be explained by what can be seen to be happening now." The principle of intrusive relationships concerns crosscutting intrusions. In geology, when an igneous intrusion cuts across a formation of sedimentary rock , it can be determined that the igneous intrusion is younger than the sedimentary rock. Different types of intrusions include stocks, laccoliths , batholiths , sills and dikes . The principle of cross-cutting relationships pertains to

1872-523: Is used for geologically young materials containing organic carbon . The geology of an area changes through time as rock units are deposited and inserted, and deformational processes alter their shapes and locations. Rock units are first emplaced either by deposition onto the surface or intrusion into the overlying rock . Deposition can occur when sediments settle onto the surface of the Earth and later lithify into sedimentary rock, or when as volcanic material such as volcanic ash or lava flows blanket

1950-679: The Baluchistan region and along the slopes of the Elburz and Zagros mountains. 200 varieties of fish live in the Persian Gulf. Thirty species of the most important commercial fish Sturgeon is found in the Caspian Sea. The Iranian plateau harvests trees for making doors, ploughs, and baskets. Fruit is grown also. Pears , apples , apricots , quince , plums , nectarines , cherries , mulberries , and peaches were commonly seen in

2028-706: The Bingöl Mountains on the borders of Varto district merge with it around the Kırıkhan village of Tekman district. It is surrounded by the Aras Mountains from the south. The Aras meets the Akhuryan River southeast of Digor . From Digor it flows along the Armenia–Turkey border , then runs close to the corridor that connects Turkey to Azerbaijan 's Nakhchivan exclave, and continues along

2106-679: The Caucasus Mountains to the northwest, the Strait of Hormuz and the Persian Gulf to the south, and the Indian subcontinent to the southeast. As a historical region, it includes Parthia , Media , Persis , and some of the previous territories of Greater Iran . The Zagros form the plateau's western boundary, and its eastern slopes may also be included in the term. The Encyclopædia Britannica excludes "lowland Khuzestan " explicitly and characterizes Elam as spanning "the region from

2184-671: The Initial Upper Paleolithic (c. 45kya) and Upper Paleolithic (c. 38kya) periods respectively. Ancient and modern populations in the Iranian plateau have a similar genetic component to the Ancient West Eurasian lineage which stayed in the 'population hub' (WEC2), but also display some ancestry from Basal Eurasians and Ancient East Eurasians via contact events starting in the Paleolithic . In

2262-804: The Kura river . It drains the south side of the Lesser Caucasus Mountains, while the Kura drains the north side of the Lesser Caucasus. The river's total length is 1,072 km (666 mi) and its watershed covers an area of 102,000 km (39,000 sq mi). The Aras is one of the longest rivers in the Caucasus. In classical antiquity, the river was known to the Greeks as Araxes ( Greek : Ἀράξης ). Its modern Armenian name

2340-747: The Mesopotamian plain to the Iranian Plateau". From the Caspian in the northwest to the Suleiman mountains in the southeast, the Iranian Plateau extends for close to 2,000 kilometres (1,200 mi). It encompasses a large part of Iran , all of Afghanistan , and the parts of Pakistan that are situated to the west of the Indus River , covering an area of some 3,700,000 square kilometres (1,400,000 sq mi) In spite of being called

2418-698: The Pontic and Taurus Mountains converge, is rugged country with higher elevations, a more severe climate, and greater precipitation than are found on the Anatolian plateau . The region is known as the Anti-Taurus , and the average elevation of its peaks exceeds 3,000 m (9,800 ft). Mount Ararat , at 5,137 meters (16,854 ft) the highest point in Turkey , is located in the Anti-Taurus. Lake Van

Iranian plateau - Misplaced Pages Continue

2496-1113: The Soviet Union built the Aras Dam near the Azerbaijani city of Nakhchivan , creating the Aras Reservoir. In 1999–2008, Iran built the Khoda Afarin Dam near the historic Khudafarin Bridges , creating the Khoda Afarin Reservoir , and the Giz Galasi Dam 12 km down the river, creating the Giz Galasi Reservoir . Iran and Armenia are planning to build the Meghri Dam near the Armenian town of Meghri . In 2006,

2574-506: The bedrock . This study is often known as Quaternary geology , after the Quaternary period of geologic history, which is the most recent period of geologic time. Magma is the original unlithified source of all igneous rocks . The active flow of molten rock is closely studied in volcanology , and igneous petrology aims to determine the history of igneous rocks from their original molten source to their final crystallization. In

2652-512: The geochemical evolution of rock units. Petrologists can also use fluid inclusion data and perform high temperature and pressure physical experiments to understand the temperatures and pressures at which different mineral phases appear, and how they change through igneous and metamorphic processes. This research can be extrapolated to the field to understand metamorphic processes and the conditions of crystallization of igneous rocks. This work can also help to explain processes that occur within

2730-402: The mantle below (separated within itself by seismic discontinuities at 410 and 660 kilometers), and the outer core and inner core below that. More recently, seismologists have been able to create detailed images of wave speeds inside the earth in the same way a doctor images a body in a CT scan . These images have led to a much more detailed view of the interior of the Earth, and have replaced

2808-650: The raptor Shikra , or Little Banded Goshawk ( Accipiter badius ), which was new to Turkey's avifauna. A Biology professor at the University of Utah and a president of the KuzeyDoğa Society, Çağan Şekercioğlu, appealed to the Ministry of Forest and Water Management to drop the Tuzluca Dam project, which would destroy the wetland harboring bird wildlife in the Aras Valley. In 2013, the ministry granted

2886-434: The relative ages of rocks found at a given location; geochemistry (a branch of geology) determines their absolute ages . By combining various petrological, crystallographic, and paleontological tools, geologists are able to chronicle the geological history of the Earth as a whole. One aspect is to demonstrate the age of the Earth . Geology provides evidence for plate tectonics , the evolutionary history of life , and

2964-440: The 1960s, it was discovered that the Earth's lithosphere , which includes the crust and rigid uppermost portion of the upper mantle , is separated into tectonic plates that move across the plastically deforming, solid, upper mantle, which is called the asthenosphere . This theory is supported by several types of observations, including seafloor spreading and the global distribution of mountain terrain and seismicity. There

3042-522: The 20th century. Almonds and pistachios are common in warmer areas. Dates , oranges , grapes , melon , and limes are also grown. Other edibles include potatoes and cauliflower , which were hard to grow until European settlement brought irrigation improvements. Other vegetables include cabbage , tomatoes , artichokes , cucumbers , spinach , radishes , lettuce , and eggplants . The plateau also produces wheat , barley , millet , beans , opium , cotton , lucerne , and tobacco . The barley

3120-515: The 489 bird species found in Turkey are recorded at this wetland, making it eastern Turkey's most species-rich wetland for birds. The number of ringed and observed 306 bird species comprises 90 percent of the 340 bird species in Iğdır Province, the most bird species rich landlocked province of Turkey. Seven new bird species were observed during the bird ringing activities in 2012 alone, including

3198-652: The Armenian people. According to a legend cited by Strabo , in ancient times, the Araxes river in Armenia had no outflow to the Caspian Sea , but spread out in plains and created a lake without outflow. In Islamic times, the Araxes became known in Arabic parlance as al-Rass (not to be confused with modern-day Ar Rass ) and in Perso-Turkish contexts as Aras . In modern history, the Aras gained significance as

Iranian plateau - Misplaced Pages Continue

3276-666: The Bronze Age, Elam stretched across the Zagros mountains, connecting Mesopotamia and the Iranian plateau. The kingdoms of Aratta , known from cuneiform sources, may have been located in the central Iranian plateau. In classical antiquity the region was known as Persia , due to the Persian Achaemenid dynasty originating in Fars . The Middle Persian Erān (whence Modern Persian Irān ) began to be used in reference to

3354-622: The Earth's past climates . Geologists broadly study the properties and processes of Earth and other terrestrial planets. Geologists use a wide variety of methods to understand the Earth's structure and evolution, including fieldwork , rock description , geophysical techniques , chemical analysis , physical experiments , and numerical modelling . In practical terms, geology is important for mineral and hydrocarbon exploration and exploitation, evaluating water resources , understanding natural hazards , remediating environmental problems, and providing insights into past climate change . Geology

3432-424: The Earth, such as subduction and magma chamber evolution. Structural geologists use microscopic analysis of oriented thin sections of geological samples to observe the fabric within the rocks, which gives information about strain within the crystalline structure of the rocks. They also plot and combine measurements of geological structures to better understand the orientations of faults and folds to reconstruct

3510-484: The Grand Canyon in the southwestern United States being a very visible example, the lower rock units were metamorphosed and deformed, and then deformation ended and the upper, undeformed units were deposited. Although any amount of rock emplacement and rock deformation can occur, and they can occur any number of times, these concepts provide a guide to understanding the geological history of an area. Geologists use

3588-966: The Iranian-Armenian and the Iranian-Azerbaijani border. The Aras is fed by several major tributaries, including the Arpa Çayı (also known as the Akhuryan), which gathers the waters from the Kars River and Lake Çıldır located in Turkey, the Hrazdan River , which empties into Lake Sevan in Armenia, and the Qareh Sū, originating from the Sabalān Mountains in northeastern Iranian Azerbaijan. The lowest point in Armenia

3666-537: The beginning of the 20th century, advancement in geological science was facilitated by the ability to obtain accurate absolute dates to geological events using radioactive isotopes and other methods. This changed the understanding of geological time. Previously, geologists could only use fossils and stratigraphic correlation to date sections of rock relative to one another. With isotopic dates, it became possible to assign absolute ages to rock units, and these absolute dates could be applied to fossil sequences in which there

3744-515: The creation of topographic gradients, causing material on the rock unit that is increasing in elevation to be eroded by hillslopes and channels. These sediments are deposited on the rock unit that is going down. Continual motion along the fault maintains the topographic gradient in spite of the movement of sediment and continues to create accommodation space for the material to deposit. Deformational events are often also associated with volcanism and igneous activity. Volcanic ashes and lavas accumulate on

3822-437: The crust, the uplift of mountain ranges, and paleo-topography. Fractionation of the lanthanide series elements is used to compute ages since rocks were removed from the mantle. Other methods are used for more recent events. Optically stimulated luminescence and cosmogenic radionuclide dating are used to date surfaces and/or erosion rates. Dendrochronology can also be used for the dating of landscapes. Radiocarbon dating

3900-570: The fault is a normal fault or a thrust fault . The principle of inclusions and components states that, with sedimentary rocks, if inclusions (or clasts ) are found in a formation, then the inclusions must be older than the formation that contains them. For example, in sedimentary rocks, it is common for gravel from an older formation to be ripped up and included in a newer layer. A similar situation with igneous rocks occurs when xenoliths are found. These foreign bodies are picked up as magma or lava flows, and are incorporated, later to cool in

3978-403: The faults are not planar or because rock layers are dragged along, forming drag folds as slip occurs along the fault. Deeper in the Earth, rocks behave plastically and fold instead of faulting. These folds can either be those where the material in the center of the fold buckles upwards, creating " antiforms ", or where it buckles downwards, creating " synforms ". If the tops of the rock units within

SECTION 50

#1732757450676

4056-483: The folds remain pointing upwards, they are called anticlines and synclines , respectively. If some of the units in the fold are facing downward, the structure is called an overturned anticline or syncline, and if all of the rock units are overturned or the correct up-direction is unknown, they are simply called by the most general terms, antiforms, and synforms. Even higher pressures and temperatures during horizontal shortening can cause both folding and metamorphism of

4134-404: The formation of faults and the age of the sequences through which they cut. Faults are younger than the rocks they cut; accordingly, if a fault is found that penetrates some formations but not those on top of it, then the formations that were cut are older than the fault, and the ones that are not cut must be younger than the fault. Finding the key bed in these situations may help determine whether

4212-541: The great folded mountain belts resulting from the collision of the Arabian Plate with the Eurasian Plate . In this definition, the Iranian plateau does not cover southwestern Iran. The plateau extends from East Azerbaijan Province in northwest of Iran (Persia) all the way to Afghanistan and Pakistan west of the Indus River . It also includes smaller parts of the Republic of Azerbaijan , Iraqi Kurdistan , and Turkmenistan . The northwestern Iranian plateau, where

4290-506: The highlands of Tibet and flows the length of Pakistan almost tracing the eastern edge of the Iranian plateau. Southeast Anatolia lies south of the Anti-Taurus Mountains. It is a region of rolling hills and a broad plateau surface that extends into Syria. Elevations decrease gradually, from about 800 meters (2,600 ft) in the north to about 500 meters (1,600 ft) in the south. Traditionally, wheat and barley are

4368-632: The history of rock deformation in the area. In addition, they perform analog and numerical experiments of rock deformation in large and small settings. Aras River The Aras (also known as the Araks , Arax , Araxes , or Araz ) is a river in the Caucasus . It rises in eastern Turkey and flows along the borders between Turkey and Armenia , between Turkey and the Nakhchivan exclave of Azerbaijan , between Iran and both Azerbaijan and Armenia, and, finally, through Azerbaijan where it flows into

4446-423: The internal composition and structure of the Earth. Seismologists can use the arrival times of seismic waves to image the interior of the Earth. Early advances in this field showed the existence of a liquid outer core (where shear waves were not able to propagate) and a dense solid inner core . These advances led to the development of a layered model of the Earth, with a lithosphere (including crust) on top,

4524-464: The later end of the scale, it is marked by the present day (in the Holocene epoch ). The following five timelines show the geologic time scale to scale. The first shows the entire time from the formation of the Earth to the present, but this gives little space for the most recent eon. The second timeline shows an expanded view of the most recent eon. In a similar way, the most recent era is expanded in

4602-454: The lowest layer to deposition of the highest bed. The principle of faunal succession is based on the appearance of fossils in sedimentary rocks. As organisms exist during the same period throughout the world, their presence or (sometimes) absence provides a relative age of the formations where they appear. Based on principles that William Smith laid out almost a hundred years before the publication of Charles Darwin 's theory of evolution ,

4680-450: The main crops of the region. The plateau's mountain ranges can be divided into five major subregions : The Iranian plateau may have played a major role in the expansion of modern humans after the Out of Africa migration , serving as 'population hub' for 'Common Eurasians', where they subsequently diverged into ' Ancient East Eurasians ' and 'Ancient West Eurasians' at c. 50,000 years ago, and from where they expanded in two waves during

4758-445: The mantle and show the crystallographic structures expected in the inner core of the Earth. The geological time scale encompasses the history of the Earth. It is bracketed at the earliest by the dates of the first Solar System material at 4.567 Ga (or 4.567 billion years ago) and the formation of the Earth at 4.54 Ga (4.54 billion years), which is the beginning of the Hadean eon  – a division of geological time. At

SECTION 60

#1732757450676

4836-405: The matrix. As a result, xenoliths are older than the rock that contains them. The principle of original horizontality states that the deposition of sediments occurs as essentially horizontal beds. Observation of modern marine and non-marine sediments in a wide variety of environments supports this generalization (although cross-bedding is inclined, the overall orientation of cross-bedded units

4914-420: The north and the Main Zagros Thrust; the suture zone between the northward moving Arabian plate and the Eurasian continent is the Iranian plateau. It is a geologically well-studied area because of general interest in continental collision zones, and because of Iran's long history of research in geology , particularly in economic geology . The Iranian plateau in geology refers to a geographical area north of

4992-569: The principles of succession developed independently of evolutionary thought. The principle becomes quite complex, however, given the uncertainties of fossilization, localization of fossil types due to lateral changes in habitat ( facies change in sedimentary strata), and that not all fossils formed globally at the same time. Geologists also use methods to determine the absolute age of rock samples and geological events. These dates are useful on their own and may also be used in conjunction with relative dating methods or to calibrate relative methods. At

5070-428: The rocks. This metamorphism causes changes in the mineral composition of the rocks; creates a foliation , or planar surface, that is related to mineral growth under stress. This can remove signs of the original textures of the rocks, such as bedding in sedimentary rocks, flow features of lavas , and crystal patterns in crystalline rocks . Extension causes the rock units as a whole to become longer and thinner. This

5148-433: The simplified layered model with a much more dynamic model. Mineralogists have been able to use the pressure and temperature data from the seismic and modeling studies alongside knowledge of the elemental composition of the Earth to reproduce these conditions in experimental settings and measure changes within the crystal structure. These studies explain the chemical changes associated with the major seismic discontinuities in

5226-429: The southwestern United States, sedimentary, volcanic, and intrusive rocks have been metamorphosed, faulted, foliated, and folded. Even older rocks, such as the Acasta gneiss of the Slave craton in northwestern Canada , the oldest known rock in the world have been metamorphosed to the point where their origin is indiscernible without laboratory analysis. In addition, these processes can occur in stages. In many places,

5304-435: The state (rather than as an ethnic designator) from the Sassanid period (see Etymology of Iran ). Archaeological sites and cultures of the Iranian plateau include: The plateau has historical oak and poplar forests. Oak forests are found around Shiraz . Aspen , elm , ash , willow , walnut , pine , and cypress are also found, though the latter two are rare. As of 1920, poplar was harvested for making doors . Elm

5382-550: The subsurface. Sub-specialities of geology may distinguish endogenous and exogenous geology. Geological field work varies depending on the task at hand. Typical fieldwork could consist of: In addition to identifying rocks in the field ( lithology ), petrologists identify rock samples in the laboratory. Two of the primary methods for identifying rocks in the laboratory are through optical microscopy and by using an electron microprobe . In an optical mineralogy analysis, petrologists analyze thin sections of rock samples using

5460-407: The surface of the Earth and the convecting mantle is called plate tectonics . The development of plate tectonics has provided a physical basis for many observations of the solid Earth . Long linear regions of geological features are explained as plate boundaries: Plate tectonics has provided a mechanism for Alfred Wegener 's theory of continental drift , in which the continents move across

5538-488: The surface of the Earth over geological time. They also provided a driving force for crustal deformation, and a new setting for the observations of structural geology. The power of the theory of plate tectonics lies in its ability to combine all of these observations into a single theory of how the lithosphere moves over the convecting mantle. Advances in seismology , computer modeling , and mineralogy and crystallography at high temperatures and pressures give insights into

5616-479: The surface, and igneous intrusions enter from below. Dikes , long, planar igneous intrusions, enter along cracks, and therefore often form in large numbers in areas that are being actively deformed. This can result in the emplacement of dike swarms , such as those that are observable across the Canadian shield, or rings of dikes around the lava tube of a volcano. All of these processes do not necessarily occur in

5694-742: The surface. Igneous intrusions such as batholiths , laccoliths , dikes , and sills , push upwards into the overlying rock, and crystallize as they intrude. After the initial sequence of rocks has been deposited, the rock units can be deformed and/or metamorphosed . Deformation typically occurs as a result of horizontal shortening, horizontal extension , or side-to-side ( strike-slip ) motion. These structural regimes broadly relate to convergent boundaries , divergent boundaries , and transform boundaries, respectively, between tectonic plates. When rock units are placed under horizontal compression , they shorten and become thicker. Because rock units, other than muds, do not significantly change in volume , this

5772-407: The third timeline, the most recent period is expanded in the fourth timeline, and the most recent epoch is expanded in the fifth timeline. Horizontal scale is Millions of years (above timelines) / Thousands of years (below timeline) Epochs: Methods for relative dating were developed when geology first emerged as a natural science . Geologists still use the following principles today as

5850-460: The valleys of the Kura and Aras. The river is also mentioned in the last chapter of Virgil's Aeneid VIII, as "angry at the bridge," since the Romans built a bridge over it so that it is thereby conquered. The river Aras has been associated with the biblical rivers Gihon and Pishon . Robert H. Hewsen described Aras as the only "true river" of Armenia and as "Mother Araxes," a symbol of pride to

5928-541: The wooded mountains of the plateau. The shores of the Caspian Sea and the Persian Gulf house aquatic birds such as seagulls , ducks , and geese . Deer, hedgehogs, foxes, and 22 species of rodents are found in semidesert, and palm squirrels and Asiatic black bears live in Baluchistan. Wide variety of amphibians and reptiles such as toads, frogs , tortoises , lizards , salamanders , racers, rat snakes ( Ptyas ), cat snakes ( Tarbophis fallax ), and vipers live

6006-615: Was datable material, converting the old relative ages into new absolute ages. For many geological applications, isotope ratios of radioactive elements are measured in minerals that give the amount of time that has passed since a rock passed through its particular closure temperature , the point at which different radiometric isotopes stop diffusing into and out of the crystal lattice . These are used in geochronologic and thermochronologic studies. Common methods include uranium–lead dating , potassium–argon dating , argon–argon dating and uranium–thorium dating . These methods are used for

6084-441: Was used for ploughs . Other trees like acacia , cypress, and Turkestan elm were used for decorative purposes. Flower wise, the plateau can grow lilac , jasmine , and roses . Hawthorn and Cercis siliquastrum are common, which are both used for basket weaving . The plateau is abundant with wildlife including leopards , bears , hyenas , wild boars , ibex , gazelles , and mouflons . These animals are mostly found in

#675324