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96-547: The Himalayan mountain chain is a fold and thrust belt that can be divided into four units bounded by thrusts from south to north: the Sub-Himalaya, Lesser Himalaya, Greater Himalaya and Tethyan Himalaya. The Lesser Himalayan Zone has a lower relief and elevation of the mountains compared to Greater Himalaya. The Lesser Himalaya Sequence (LHS) is bounded by two main thrusts: the Main Central Thrust (MCT) in

192-631: A Late Cretaceous - Palaeocene age based on faunal evidence. In terms of depositional environment, the dominance of limestone in the Singtali Formation and sparse fauna would imply shallow marine conditions at that time. A high-energy, agitated environment can be inferred from the presence of ooids . The Subathu Formation also belongs to the Sirmur Group of the Outer Lesser Himalaya of Garhwal. In 2020 literature it

288-518: A Permian age. Generally, the strata here are lenticular and display a fining-upwards sequence. In tectonic context, it is proposed that the Gondwana strata here have experienced post—Gondwana orogenic movements , resulting in folded rocks followed by overturned beddings. Following a sedimentary break or unconformity, the Singtali and Subathu formations were deposited as foreland basin sediments in

384-722: A brackish or fresh water environment, indicating a gradual and minor regression period. The regression phase was probably initiated by the sea level change in the northern Neotethys. However, overall there were no significant changes in tectonic setting during the Early Cretaceous to Early Paleocene . In fact, the Bhainskati Formation is correlated to the Subathu Formation in the Garhwal Himalaya. The deposition of these marine facies in

480-472: A constant rate. These " molecular clocks ", however, are fallible, and provide only approximate timing: for example, they are not sufficiently precise and reliable for estimating when the groups that feature in the Cambrian explosion first evolved, and estimates produced by different techniques may vary by a factor of two. Organisms are only rarely preserved as fossils in the best of circumstances, and only

576-425: A depositional environment of a protected lagoon or embayment , while the overlying siltstone is deposited in a mud flat of an intertidal zone . The Upper Tal can be subdivided into lower quartzitic sequence and upper thick calcareous sequence containing abundant fragmentary shells of bivalves , gastropods , bryozoa , etc. The Phulchatti quartzite succession represents the deposits of a shoal environment, while

672-433: A fold and thrust belt, the belt propagates into its foreland. New thrusts develop at the front of the belt, folding the older thrusts that have become inactive. This sequential propagation of thrusts into the foreland is the most common. Thrusts that form within the belt rather than at the thrust front are known as "out-of-sequence". In map view, fold and thrust belts are generally sinuous rather than completely linear. Where

768-426: A fraction of such fossils have been discovered. This is illustrated by the fact that the number of species known through the fossil record is less than 5% of the number of known living species, suggesting that the number of species known through fossils must be far less than 1% of all the species that have ever lived. Because of the specialized and rare circumstances required for a biological structure to fossilize, only

864-499: A hierarchical classification system still in use today. Darwin and his contemporaries first linked the hierarchical structure of the tree of life with the then very sparse fossil record. Darwin eloquently described a process of descent with modification, or evolution, whereby organisms either adapt to natural and changing environmental pressures, or they perish. When Darwin wrote On the Origin of Species by Means of Natural Selection, or

960-639: A marine facies Tertiary Unit. The Gondwana strata are mainly developed within two zones in Nepal in the central Himalaya. The first is in central Nepal, where several outcrops of the Tansen Group can be found. The second is in western Nepal, where the Gondwana strata are exposed in the Jumla – Humla basins near the Tethyan Himalaya. The Tansen area contains Gondwana sediments that are identified by

1056-418: A mid-Ordovician age. Such index fossils must be distinctive, be globally distributed and occupy a short time range to be useful. Misleading results are produced if the index fossils are incorrectly dated. Stratigraphy and biostratigraphy can in general provide only relative dating ( A was before B ), which is often sufficient for studying evolution. However, this is difficult for some time periods, because of

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1152-536: A mutation first appeared. Phylogenetics and paleontology work together in the clarification of science's still dim view of the appearance of life and its evolution. Niles Eldredge 's study of the Phacops trilobite genus supported the hypothesis that modifications to the arrangement of the trilobite's eye lenses proceeded by fits and starts over millions of years during the Devonian . Eldredge's interpretation of

1248-570: A portion of the deceased organism, usually that portion that was partially mineralized during life, such as the bones and teeth of vertebrates , or the chitinous or calcareous exoskeletons of invertebrates . Fossils may also consist of the marks left behind by the organism while it was alive, such as animal tracks or feces ( coprolites ). These types of fossil are called trace fossils or ichnofossils , as opposed to body fossils . Some fossils are biochemical and are called chemofossils or biosignatures . Gathering fossils dates at least to

1344-400: A richly diverse assembly of early multicellular eukaryotes . The fossil record and faunal succession form the basis of the science of biostratigraphy or determining the age of rocks based on embedded fossils. For the first 150 years of geology , biostratigraphy and superposition were the only means for determining the relative age of rocks. The geologic time scale was developed based on

1440-603: A shallow marine environment is associated with the foreland basin development. The Early Tertiary geology of the Indian Lesser Himalaya conforms well with the classic foreland basin model. In Late Cretaceous times, this area of the northern region of the Indian Plate finally became submerged after a long period when sub-aerial conditions had dominated. This resulted in deposition of the marine Singtali Formation. A possible explanation for this event

1536-448: A small percentage of life-forms can be expected to be represented in discoveries, and each discovery represents only a snapshot of the process of evolution. The transition itself can only be illustrated and corroborated by transitional fossils, which will never demonstrate an exact half-way point. The fossil record is strongly biased toward organisms with hard-parts, leaving most groups of soft-bodied organisms with little to no role. It

1632-441: A tectonic setting related to basaltic volcanism as the volcanic clasts were derived from the underlying lava and transported by rivers from Gondwana land. The interbedding layers of fluvial sediments and basaltic lava bands imply that there was repeated occurrence of basaltic eruption and erosion and sedimentation of fluvial deposits alternatively. These events were probably caused by breaking up and rifting of Gondwanaland during

1728-449: Is a notable example of how knowledge encoded by the fossil record continues to contribute otherwise unattainable information on the emergence and development of life on Earth. For example, the research suggests Markuelia has closest affinity to priapulid worms, and is adjacent to the evolutionary branching of Priapulida , Nematoda and Arthropoda . Despite significant advances in uncovering and identifying paleontological specimens, it

1824-412: Is any preserved remains, impression, or trace of any once-living thing from a past geological age . Examples include bones , shells , exoskeletons , stone imprints of animals or microbes , objects preserved in amber , hair , petrified wood and DNA remnants. The totality of fossils is known as the fossil record . Though the fossil record is incomplete, numerous studies have demonstrated that there

1920-538: Is enough information available to give a good understanding of the pattern of diversification of life on Earth. In addition, the record can predict and fill gaps such as the discovery of Tiktaalik in the arctic of Canada . Paleontology includes the study of fossils: their age, method of formation, and evolutionary significance. Specimens are usually considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years to 4.1 billion years old. The observation in

2016-600: Is found. Ripples and cross-laminae can be observed on the greywacke, while small-scaled sun cracks and slump folds can be seen on shale. It is proposed that this sequence has a depositional environment of semi-isolated basin. The marine fossils contained here indicate a Permian age of the Setikhola Formation. The uppermost Gondwana unit is the Damudas Sub-Group, which is characterized by arenite , shale , slate and black coal beds . In fact,

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2112-479: Is generally accepted that the fossil record is vastly incomplete. Approaches for measuring the completeness of the fossil record have been developed for numerous subsets of species, including those grouped taxonomically, temporally, environmentally/geographically, or in sum. This encompasses the subfield of taphonomy and the study of biases in the paleontological record. Paleontology seeks to map out how life evolved across geologic time. A substantial hurdle

2208-928: Is probably the contact between the Upper Amile Formation and the overlying Bhainskati Formation of the Tertiary Unit. The Amile Formation is dated to the Early Cretaceous to Early Paleocene , while the Bhainskati Formation is biostratigraphically dated as from the Middle to Late Eocene . In the Jumla area of western Nepal, Gondwana strata unconformably overly the caronbate rocks of the Uppermost Nawakot Unit of Mesoproterozoic age. The Gondwanas here are characterized by quartzose sandstones , black shales , quartz pebble conglomerates as well as coal and lignite . They are dated as Jurassic to Paleocene . The lithology of Gondwanas here

2304-597: Is quite similar to that of the Amile Formation in central Nepal. Also, the Gondwana Unit is overlain by the Bhainskati Formation of the Tertiary Unit, similar to the situation in central Nepal. However, in fact, the Gondwana Unit is not very well developed in the Jumla area. The strata with lithology similar to that of the Taltung Formation and Lower Gondwanas are missing here. In other words,

2400-400: Is referred to as Subathu Group. It is a sequence of limestones , green mudrocks and subordinate sandstones , and has been paleontologically dated as from Late Palaeocene to Middle Eocene . The rocks are rich in fossils . The limestones with normal marine fauna and thick mudstones with well preserved, burrowing-type molluscs indicate a quiet, relatively shallow shelf environment during

2496-520: Is related to extensional tectonics , such that India has drifted and detached from Gondwana , and northwards subduction of the Neotethys (Tethys Ocean) beneath Asia occurred. Therefore, the Singtali Formation has been interpreted as pre-collisional transgressive sediments, at the same time there was a global eustatic sea level rise during the Late Cretaceous . The tectonic setting of

2592-438: Is replete with the mollusks , the vertebrates , the echinoderms , the brachiopods and some groups of arthropods . Fossil sites with exceptional preservation—sometimes including preserved soft tissues—are known as Lagerstätten —German for "storage places". These formations may have resulted from carcass burial in an anoxic environment with minimal bacteria, thus slowing decomposition. Lagerstätten span geological time from

2688-692: Is that ophiolites such as the Spontang ophiolite were obducted onto the Indian Plate Zanskar continental shelf in the Campanian or Maastrichtian , resulting in downward displacement and flexure of the Indian Plate hundreds of kilometres to the south. Moreover, it has been proposed that the marine transgression is related to extensional tectonic setting, such that the Late Albian has detached from India and has started to drift from

2784-470: Is the difficulty of working out fossil ages. Beds that preserve fossils typically lack the radioactive elements needed for radiometric dating . This technique is our only means of giving rocks greater than about 50 million years old an absolute age, and can be accurate to within 0.5% or better. Although radiometric dating requires careful laboratory work, its basic principle is simple: the rates at which various radioactive elements decay are known, and so

2880-413: Is the science of deciphering the "layer-cake" that is the sedimentary record. Rocks normally form relatively horizontal layers, with each layer younger than the one underneath it. If a fossil is found between two layers whose ages are known, the fossil's age is claimed to lie between the two known ages. Because rock sequences are not continuous, but may be broken up by faults or periods of erosion , it

2976-467: Is very difficult to match up rock beds that are not directly adjacent. However, fossils of species that survived for a relatively short time can be used to match isolated rocks: this technique is called biostratigraphy . For instance, the conodont Eoplacognathus pseudoplanus has a short range in the Middle Ordovician period. If rocks of unknown age have traces of E. pseudoplanus , they have

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3072-801: The Cambrian period to the present . Worldwide, some of the best examples of near-perfect fossilization are the Cambrian Maotianshan Shales and Burgess Shale , the Devonian Hunsrück Slates , the Jurassic Solnhofen Limestone , and the Carboniferous Mazon Creek localities. A fossil is said to be recrystallized when the original skeletal compounds are still present but in a different crystal form, such as from aragonite to calcite . Replacement occurs when

3168-478: The Early Cretaceous . The Amile Formation is unconformably overlying the Taltung Formation. It is dominated by white quartz arenites , quartz pebble sandstones , carbonaceous shales and limestones with coral , mollusc and vertebrate fossils . In the upper part of the formation, an abrupt change of lithology from thick, coarse-grained quartzose sandstones to interbedded layers of black marine shales and fine-grained quartzose sandstones are observed. This

3264-717: The Indian subcontinent , interrupting the sedimentation in the Lesser Himalaya and causing a widespread unconformity in Nepal. This is known as the Great Lesser Himalayan Unconformity, which separates the older LHS from the overlying younger LHS that has an age of Permian to Middle Eocene . During the Paleozoic and Mesozoic , the LHS starts from the basal Tal Formation, which is part of

3360-659: The Late Carboniferous to the Permian . The Upper Gondwanas are further subdivided into the Taltung and Amile formations. The Taltung Formation is characterised by coarse-grained, volcaniclastic conglomerates , sandstones and silty shales . They were deposited by northwestward-flowing fluvial channels. Abundant plant fossils are found in the Taltung Formation, and they are dated to the Late Jurassic to

3456-558: The Late Cretaceous to Palaeocene , followed by the Subathu Formation, which was deposited from the Late Palaeocene to Middle Eocene , marking the start of Cenozoic Era. Table showing the major formations discussed in the following sections: (Late Paleocene – Middle Eocene) (Late Carboniferous – Permian) (Late Cretaceous – Paleocene) (Jurassic – Paleocene) Upper and Lower Gondwanas (Late Permo-Carboniferous – Paleocene) (Cambrian) The Tal Formation belongs to

3552-489: The Late Jurassic to Early Cretaceous . The whole sequence of Upper Gondwanas (including both the Taltung and Amile Formations) represents non-marine deposition. Data from the paleocurrent direction show that the sediments were derived from the south, because the Indian subcontinent was drifting northwards towards the Lesser Himalaya. After that, the Bhainskati Formation was deposited in shallow marine environment. The upper Bhainskati has been found to have been deposited in

3648-542: The Late Paleozoic . The Diuri Formation is then overlain by the Setikhola Formation, which is characterized by feldspathic sandstone , shale , graywacke , coal lenses and plant fossils . One sequence consists of interbedding of sandstone and shale and is intensely bioturbated with flames structures observed as well. This indicates a depositional environment of beach or mudflat . Also, another sequence of interbedding calcareous greywacke and carbonaceous shale

3744-586: The Phacops fossil record was that the aftermaths of the lens changes, but not the rapidly occurring evolutionary process, were fossilized. This and other data led Stephen Jay Gould and Niles Eldredge to publish their seminal paper on punctuated equilibrium in 1971. Synchrotron X-ray tomographic analysis of early Cambrian bilaterian embryonic microfossils yielded new insights of metazoan evolution at its earliest stages. The tomography technique provides previously unattainable three-dimensional resolution at

3840-569: The Renaissance . Leonardo da Vinci concurred with Aristotle's view that fossils were the remains of ancient life. For example, Leonardo noticed discrepancies with the biblical flood narrative as an explanation for fossil origins: If the Deluge had carried the shells for distances of three and four hundred miles from the sea it would have carried them mixed with various other natural objects all heaped up together; but even at such distances from

3936-602: The Song dynasty during the 11th century, who kept a specific seashell fossil with his own poem engraved on it. In his Dream Pool Essays published in 1088, Song dynasty Chinese scholar-official Shen Kuo hypothesized that marine fossils found in a geological stratum of mountains located hundreds of miles from the Pacific Ocean was evidence that a prehistoric seashore had once existed there and shifted over centuries of time . His observation of petrified bamboos in

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4032-407: The forelands adjacent to major orogens as deformation propagates outwards. Fold and thrust belts usually comprise both folds and thrust faults , commonly interrelated. They are commonly also known as thrust-and-fold belts, or simply thrust-fold belts. Fold and thrust belts are formed of a series of sub-parallel thrust sheets, separated by major thrust faults. As the total shortening increases in

4128-402: The law of superposition ) preserved different assemblages of fossils, and that these assemblages succeeded one another in a regular and determinable order. He observed that rocks from distant locations could be correlated based on the fossils they contained. He termed this the principle of faunal succession . This principle became one of Darwin's chief pieces of evidence that biological evolution

4224-403: The thunderbird . There is no such direct mythological connection known from prehistoric Africa, but there is considerable evidence of tribes there excavating and moving fossils to ceremonial sites, apparently treating them with some reverence. In Japan, fossil shark teeth were associated with the mythical tengu , thought to be the razor-sharp claws of the creature, documented some time after

4320-453: The 16th century. Roman naturalist Pliny the Elder wrote of " tongue stones ", which he called glossopetra . These were fossil shark teeth, thought by some classical cultures to look like the tongues of people or snakes. He also wrote about the horns of Ammon , which are fossil ammonites , whence the group of shelled octopus-cousins ultimately draws its modern name. Pliny also makes one of

4416-739: The 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils. The development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure the absolute ages of rocks and the fossils they host. There are many processes that lead to fossilization , including permineralization , casts and molds, authigenic mineralization , replacement and recrystallization, adpression, carbonization , and bioimmuration. Fossils vary in size from one- micrometre (1 μm) bacteria to dinosaurs and trees, many meters long and weighing many tons. A fossil normally preserves only

4512-413: The 8th century AD. In medieval China, the fossil bones of ancient mammals including Homo erectus were often mistaken for " dragon bones" and used as medicine and aphrodisiacs . In addition, some of these fossil bones are collected as "art" by scholars, who left scripts on various artifacts, indicating the time they were added to a collection. One good example is the famous scholar Huang Tingjian of

4608-678: The Garhwal Outer Lesser Himalaya during the Late Cretaceous to Middle Palaeocene. Both formations can be found overlying the Tal Formation in an extremely complex structural setting including isoclinal overturned folding and multiple thrusting events. In addition, with the similarities of the lithology as well as depositional environment, it is sometimes quite difficult to distinguish between the Singtali and Subathu Formations. The main difference discussed in

4704-463: The Gondwana supercontinent, Also, the Neotethys has subducted northwards beneath Asia. This event is accompanied with the Late Cretaceous global eustatic sea-level high stand as well. The initial contact between India and Eurasia have taken place at 62 – 60 Ma in the northwestern Himalayas, with terminal collision culminating by 55 Ma in the east. The Subathu Formation rocks were deposited during

4800-632: The Jumla area), resulting in missing Gondwana Strata in Jumla during the Mesozoic (see more in the table of "Gondwana Strata of LHS in Western and Central Nepal"). In the Central and Eastern Himalaya, Gondwana strata from the Permian to Paleocene were preserved unconformably onto the older LHS. The next succession of the LHS in the Garhwal Himalaya comes to the Singtali Formation, which was deposited from

4896-520: The LHS in the Jumla area is lacking a part of the Gondwana Unit of age ranging from Late Carboniferous- Permian to Early Cretaceous . This is probably due to a greater effect by the Great Lesser Himalayan Unconformity in the Jumla area than in the Tansen area. Compared with Nepal, the Gondwana strata are exposed in a relatively smaller area in Bhutan . In southeastern Bhutan, the basal LHS begins with

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4992-533: The Lower Gondwana glacial diamictite is unconformably overlain by the fluvial Taltung Formation (Upper Gondwana), which contains abundant plant fossils distributed widely within the Tansen area. Alkali basalt lava flows are interbedded with the fluvial beds in the Lower Taltung. Gravelly braided river facies are shown in the Lower Taltung while silty meandering river facies are displayed in

5088-795: The Mussoorie Group of Outer Lesser Himalaya of Garhwal in northwestern India. It is well exposed along the Krol Belt, and is overlying the Precambrian Krol Group. The Tal in the Mussoorie Synform can be divided into the Lower Tal and Upper Tal. For the Lower Tal, there are four subdivisions: the Chert, Argillaceous, Arenaceous and Calcareous Units. The basal black shale succession with sandy limestone represents

5184-676: The Outer Lesser Himalayan sequence in the Garhwal Himalaya. The Tal was deposited between the period of the Late Proterozoic to Palaeozoic Cambrian . After that, there was a great hiatus between the Middle Proterozoic rocks and the overlying Palaeocene - Eocene strata. This indicates that the LHS experienced a long period of denudation or non-deposition in the Western Himalaya (e.g. in

5280-615: The Preservation of Favoured Races in the Struggle for Life , the oldest animal fossils were those from the Cambrian Period, now known to be about 540 million years old. He worried about the absence of older fossils because of the implications on the validity of his theories, but he expressed hope that such fossils would be found, noting that: "only a small portion of the world is known with accuracy." Darwin also pondered

5376-566: The Proterozoic and deeper still in the Archean is only "recounted by microscopic fossils and subtle chemical signals." Molecular biologists, using phylogenetics , can compare protein amino acid or nucleotide sequence homology (i.e., similarity) to evaluate taxonomy and evolutionary distances among organisms, with limited statistical confidence. The study of fossils, on the other hand, can more specifically pinpoint when and in what organism

5472-481: The Setikhola Formation and Damudas Sub-Group are together termed as the Gondwana succession. The bedrock of the Damudas Sub-Group is made up of gritty, micaceous and cross-laminated sandstones . These friable sandstone layers are interbedded with coal beds that have been sheared and crushed. Abundant plant fossils like fern leaves can be found on the carbonaceous shale, characterising the Damuda coalfields and indicating

5568-467: The Subathu Formation is different from that of the Singtali Formation. It was deposited during the suturing of India and Eurasia, between the initial and terminal continental collision . The inferred pattern of northward shallowing and reduced sedimentation conflicts with classic foreland basin models. However, these depositional patterns may reflect basement fault reactivation, giving rise to paleohighs, rather than simply crustal loading following on from

5664-682: The Subathu Formation is only partially preserved in the Krol nappe and under the Garhwal thrust, and unconformably overlies the Tal Formation. In the Singtali Formation times ( Late Cretaceous - Palaeocene ), the Indian craton submerged and stable shallow marine conditions ensued. This event is possibly related to flexure , such that the Spontang ophiolite was obducted onto the Northern Indian Plate margin. One more possible explanation

5760-540: The Upper Taltung, as a result, the sequence is fining upwards. The strata were deposited in a terrestrial basin on Gondwana. Because of the appearance of glacial diamictite and index plant fossils found in the Lower and Upper Gondwanas respectively, it has been proposed that the Lesser Himalaya had been a part of Gondwanaland during the Permian to Cretaceous . Later on, the presence of basaltic lava flows indicate

5856-454: The base of this formation, pebbles are composed of quartzite and siliceous dolomite. They are embedded in a fine quartzite matrix. The thicker beds of slate and phyllite are overlying the conglomerate layers. Clear schistosity can be observed. The diamictite found implies a source of glacial origin. It is probably correlated to the glaciation event of the Gondwana supercontinent during

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5952-413: The beach, indicating the fossils were once living animals. He had previously explained them in terms of vaporous exhalations , which Persian polymath Avicenna modified into the theory of petrifying fluids ( succus lapidificatus ). Recognition of fossil seashells as originating in the sea was built upon in the 14th century by Albert of Saxony , and accepted in some form by most naturalists by

6048-714: The beginning of recorded history. The fossils themselves are referred to as the fossil record. The fossil record was one of the early sources of data underlying the study of evolution and continues to be relevant to the history of life on Earth . Paleontologists examine the fossil record to understand the process of evolution and the way particular species have evolved. Fossils have been visible and common throughout most of natural history, and so documented human interaction with them goes back as far as recorded history, or earlier. There are many examples of paleolithic stone knives in Europe, with fossil echinoderms set precisely at

6144-464: The collision. Their individual tectonic significance related to foreland basin evolution are discussed in greater detail in the next section. The general similarities and differences between the Singtali and Subathu formations are shown in the table below: Neotethyan subduction beneath Asia ; Continued northward drift of India after detachment from Gondwana In the Nepal Himalaya,

6240-670: The deity Sopdu , the Morning Star, equivalent of Venus in Roman mythology. Fossils appear to have directly contributed to the mythology of many civilizations, including the ancient Greeks. Classical Greek historian Herodotos wrote of an area near Hyperborea where gryphons protected golden treasure. There was indeed gold mining in that approximate region , where beaked Protoceratops skulls were common as fossils. A later Greek scholar, Aristotle , eventually realized that fossil seashells from rocks were similar to those found on

6336-466: The dry northern climate zone of what is now Yan'an , Shaanxi province, China, led him to advance early ideas of gradual climate change due to bamboo naturally growing in wetter climate areas. In medieval Christendom , fossilized sea creatures on mountainsides were seen as proof of the biblical deluge of Noah's Ark . After observing the existence of seashells in mountains, the ancient Greek philosopher Xenophanes (c. 570 – 478 BC) speculated that

6432-415: The earlier known references to toadstones , thought until the 18th century to be a magical cure for poison originating in the heads of toads, but which are fossil teeth from Lepidotes , a Cretaceous ray-finned fish. The Plains tribes of North America are thought to have similarly associated fossils, such as the many intact pterosaur fossils naturally exposed in the region, with their own mythology of

6528-550: The earliest known stromatolites are over 3.4 billion years old. The fossil record is life's evolutionary epic that unfolded over four billion years as environmental conditions and genetic potential interacted in accordance with natural selection. The Virtual Fossil Museum Paleontology has joined with evolutionary biology to share the interdisciplinary task of outlining the tree of life, which inevitably leads backwards in time to Precambrian microscopic life when cell structure and functions evolved. Earth's deep time in

6624-464: The earth during earthquake and subsidences, and petrifies whatever comes into contact with it. As a matter of fact, the petrifaction of the bodies of plants and animals is not more extraordinary than the transformation of waters. From the 13th century to the present day, scholars pointed out that the fossil skulls of Deinotherium giganteum , found in Crete and Greece, might have been interpreted as being

6720-407: The east allowing a longer period where marine conditions could predominate. This progressive suturing , however, would not explain the thickness difference between the lowest and intermediate structural levels. As the intermediate structural level restores further to the north than the lower structural level, northward shallowing of the basin (i.e. towards the load) is implied. This is different from

6816-478: The existence of a world previous to ours, destroyed by some kind of catastrophe. Interest in fossils, and geology more generally, expanded during the early nineteenth century. In Britain, Mary Anning 's discoveries of fossils, including the first complete ichthyosaur and a complete plesiosaurus skeleton, sparked both public and scholarly interest. Early naturalists well understood the similarities and differences of living species leading Linnaeus to develop

6912-589: The following is related to the tectonic events during their deposition. The Singtali Formation belongs to the Sirmur Group of the Outer Lesser Himalaya of Garhwal . It is also called "Upper Tal" as the uppermost Manikot Shell Limestone, however, this formation is distinct from the basement Tal Formation upon which it rests unconformably. Its main lithology is dominated by sandy, oolitic and shelly limestones with subordinate quartz arenites . Medium-bedded massive strata are predominant and no sedimentary structures are visible. The Singtali Formation has been assigned as

7008-519: The hand grip, dating back to Homo heidelbergensis and Neanderthals . These ancient peoples also drilled holes through the center of those round fossil shells, apparently using them as beads for necklaces. The ancient Egyptians gathered fossils of species that resembled the bones of modern species they worshipped. The god Set was associated with the hippopotamus , therefore fossilized bones of hippo-like species were kept in that deity's temples. Five-rayed fossil sea urchin shells were associated with

7104-535: The limits of fossilization. Fossils of two enigmatic bilaterians, the worm-like Markuelia and a putative, primitive protostome , Pseudooides , provide a peek at germ layer embryonic development. These 543-million-year-old embryos support the emergence of some aspects of arthropod development earlier than previously thought in the late Proterozoic. The preserved embryos from China and Siberia underwent rapid diagenetic phosphatization resulting in exquisite preservation, including cell structures. This research

7200-748: The metamorphic Daling-Shumar Group, followed by the Baxa Group that is characterized by quartzite , phyllite and dolomite succession of Neoproterozoic to probably Cambrian age. The bottom of the Gondwana Units (Diuri Formation) is then directly overlying the Baxa Group. Generally, there are three main formations of Gondwana Units exposed in southeastern Bhutan. The bottom one is the Diuri Formation with Proterozoic to Permian ages. It consists of conglomerate , quartzite , phyllite as well as diamictite with interbedded slates . At

7296-626: The north and the Main Boundary Thrust (MBT) in the south. The main layers of the LHS includes non-fossiliferous, low-grade, metasedimentary rocks, metavolcanic strata and augen gneiss . These have been dated as an age ranging from 1870 Ma to 520 Ma (i.e. Proterozoic to Cambrian ). Near the end of the Early Cambrian , there was a regional diastrophism (i.e. deformation of the Earth's crust) or crustal movement that heaved up

7392-494: The older LHS with age ranging from the Paleoproterozoic to uppermost Precambrian are separated from the younger LHS by the Great Lesser Himalayan Unconformity. Missing Early Proterozoic strata of the LHS suggest that the rocks may have been eroded before the deposition of the Gondwana strata. Younger continental facies Gondwana strata were first deposited after the unconformity. They are then unconformably overlain by

7488-426: The period of deposition. This depositional environment is similar to that of the Singtali Formation. The Subathu contains the oldest Himalayan foreland basin rocks. Near the Krol and Garhwal thrusts in northeastern India, the Subathu Formation exists as a narrow and discontinuous strip, indicating that it has experienced extremely high tectonic shearing and shattering as a result of overthrusting of rocks. Consequently,

7584-625: The presence of fossils . Two major formation can be found there. They are older Sisne Formation (or the Lower Gondwanas) and younger Taltung and Amile formations (or the Upper Gondwanas). The Sisne Formation is dominated by glacial diamictite and fluvial deposits. In the upper part of the formation, shales are found to contain fenstellid bryozoan fossils , indicating that the Lower Gondwanas in central Nepal dates from

7680-582: The probable distal nature of the basin, therefore, explaining the thin sequences of the western intermediate structural level localities. After suturing, fluvial facies are overlying the marine Subathu Formation. It is associated with the uplift of Himalaya and regression of sea in the Late Eocene. Fold and thrust belt A fold and thrust belt (FTB) is a series of mountainous foothills adjacent to an orogenic belt , which forms due to contractional tectonics . Fold and thrust belts commonly form in

7776-545: The problems involved in matching rocks of the same age across continents . Family-tree relationships also help to narrow down the date when lineages first appeared. For instance, if fossils of B or C date to X million years ago and the calculated "family tree" says A was an ancestor of B and C, then A must have evolved earlier. It is also possible to estimate how long ago two living clades diverged, in other words approximately how long ago their last common ancestor must have lived, by assuming that DNA mutations accumulate at

7872-443: The ratio of the radioactive element to its decay products shows how long ago the radioactive element was incorporated into the rock. Radioactive elements are common only in rocks with a volcanic origin, and so the only fossil-bearing rocks that can be dated radiometrically are volcanic ash layers, which may provide termini for the intervening sediments. Consequently, palaeontologists rely on stratigraphy to date fossils. Stratigraphy

7968-462: The relative ages of rock strata as determined by the early paleontologists and stratigraphers . Since the early years of the twentieth century, absolute dating methods, such as radiometric dating (including potassium/argon , argon/argon , uranium series , and, for very recent fossils, radiocarbon dating ) have been used to verify the relative ages obtained by fossils and to provide absolute ages for many fossils. Radiometric dating has shown that

8064-429: The sea and that they were still living when the strait of Gibraltar was cut through. In the mountains of Parma and Piacenza multitudes of shells and corals with holes may be seen still sticking to the rocks.... In 1666, Nicholas Steno examined a shark, and made the association of its teeth with the "tongue stones" of ancient Greco-Roman mythology, concluding that those were not in fact the tongues of venomous snakes, but

8160-423: The sea we see the oysters all together and also the shellfish and the cuttlefish and all the other shells which congregate together, found all together dead; and the solitary shells are found apart from one another as we see them every day on the sea-shores. And we find oysters together in very large families, among which some may be seen with their shells still joined together, indicating that they were left there by

8256-586: The skulls of the Cyclopes of Greek mythology , and are possibly the origin of that Greek myth. Their skulls appear to have a single eye-hole in the front, just like their modern elephant cousins, though in fact it's actually the opening for their trunk. In Norse mythology , echinoderm shells (the round five-part button left over from a sea urchin) were associated with the god Thor , not only being incorporated in thunderstones , representations of Thor's hammer and subsequent hammer-shaped crosses as Christianity

8352-467: The sudden appearance of many groups (i.e. phyla ) in the oldest known Cambrian fossiliferous strata. Since Darwin's time, the fossil record has been extended to between 2.3 and 3.5 billion years. Most of these Precambrian fossils are microscopic bacteria or microfossils . However, macroscopic fossils are now known from the late Proterozoic. The Ediacara biota (also called Vendian biota) dating from 575 million years ago collectively constitutes

8448-432: The suturing and initial collision of India and Eurasia. However, the western intermediate structural level localities show a much thinner Subathu marine sequence compared to the eastern intermediate structural level localities and the lowest structural level. The thickness variations between the west and the east could be explained by the progressive suturing of India and Eurasia from northwest to east, with later suturing in

8544-451: The teeth of some long-extinct species of shark. Robert Hooke (1635–1703) included micrographs of fossils in his Micrographia and was among the first to observe fossil forams . His observations on fossils, which he stated to be the petrified remains of creatures some of which no longer existed, were published posthumously in 1705. William Smith (1769–1839) , an English canal engineer, observed that rocks of different ages (based on

8640-494: The theoretical model, where the depocentre is close to the load and shallows towards the craton . In the Lesser Himalayan early foreland basin , palaeohighs, which are resulted from basement fault reactivation, may have been located in the west between the load to the north and the marine Subathu basin to the south. This would result in shallowing towards, and reduced sedimentation on the palaeohigh, which coupled with

8736-456: The thrust front bulges out in the direction of tectonic transport, a salient is formed. Between the bulges the areas are known as recesses , reentrants or sometimes embayments . Much of this table is adapted from Nemcok et al. , 2005 This tectonics article is a stub . You can help Misplaced Pages by expanding it . Body fossils A fossil (from Classical Latin fossilis , lit.   ' obtained by digging ' )

8832-649: The uppermost Manikot Shell Limestone, which has been proposed to have been formed in the Late Cretaceous and unconformably overlain by the Subathu Formation in the Tal Valley, Garhwal Himayala. The details of lithologies and depositional environment of Tal Formation are shown in the table below: Gondwana strata are not exposed in the Garhwal Himalaya after the Tal Formation owing to the great hiatus; some outcrops can be found in Central and Eastern Himalaya during Late Paleozoic to Mesozoic times. In Nepal ,

8928-664: The uppermost shell limestone sequence indicates an increasing energy of the shallow tidal sea, and a marine transgression in the Cretaceous . There is an increase of energy for deposition from the Lower Tal to the Upper Tal. Because of the lack of well-defined body fossils in the Tal, it has been proposed that the deposits of the Tal were formed in the Late Precambrian near Precambrian - Cambrian transition, except for

9024-524: The world was once inundated in a great flood that buried living creatures in drying mud. In 1027, the Persian Avicenna explained fossils' stoniness in The Book of Healing : If what is said concerning the petrifaction of animals and plants is true, the cause of this (phenomenon) is a powerful mineralizing and petrifying virtue which arises in certain stony spots, or emanates suddenly from

9120-458: Was adopted, but also kept in houses to garner Thor's protection. These grew into the shepherd's crowns of English folklore, used for decoration and as good luck charms, placed by the doorway of homes and churches. In Suffolk , a different species was used as a good-luck charm by bakers, who referred to them as fairy loaves , associating them with the similarly shaped loaves of bread they baked. More scientific views of fossils emerged during

9216-408: Was real. Georges Cuvier came to believe that most if not all the animal fossils he examined were remains of extinct species. This led Cuvier to become an active proponent of the geological school of thought called catastrophism . Near the end of his 1796 paper on living and fossil elephants he said: All of these facts, consistent among themselves, and not opposed by any report, seem to me to prove

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