Fossil Lagerstätten

During the Late Kaskaskia (Cratonic Sequence 3), what type of deposition predominated on the craton?

In the following space, explain the role of fossils in developing the Geologic column. Your explanation must be between 200 and 300 words.

At the beginning of the Tertiary, there is a layer of andesite breccia -a fast cooling extrusive rock that has not traveled far from its original deposition. This indicates a volcanic depositional environment. This formation was then intruded by intrusive slower cooling rocks that create a noncomformity between it and the Walker formation. The tuff breccia in the Walker formation is consistent with the same depositional environment as the andesite breccia formation as they are both extrusive rocks. It is possible that there was an eruption from a volcano that deposited the highly viscous andesite rocks followed by slower falling ash, which was then

The Sangre de Cristo Mountains are a structurally complex block having a Precambrian igneous core that is bounded by major, high-angle reverse faults and highly contorted, steeply dipping to overturned sedimentary beds of Paleozoic and Mesozoic age. The range resulted from uplift and eastward thrusting during the Laramide orogeny commencing in Late Cretaceous time and continuing intermittently to possibly late Tertiary time (Wanek and Read, 1956).

However, Hildebrand, (2009, 2013) affiliate the pre Cretaceous rocks, particularly the Neoproterozoic rocks crops out in central and east Utah, to the microcontinent Rubia, but such interpretation needs translation of rocks for a very long

Sedimentary rocks interpret dinosaur habitats through encased environmental structures of the past. Through sedimentary rocks, paleoecologists’ can examine the arranged formation of sedimentary structures to specify what type of environment the dinosaurs’ lived in. An example of a specific sedimentary rock structure can be seen through formed weathering and ripple marks by how wind and sand formed distinct patterns in the past layered sediment. These arrangements provide interpretations on the structure of the sediment and the habitat of encased fossils, through modern day comparisons

The author and his colleagues chose to focus on 375 million year old rocks in their search for fossils because amphibians that look dissimilar to fish were discovered in 365 million year old rocks, while fish without amphibian characteristics were discovered in 385 million year old rocks. Thus, it is possible that the evolutionary intermediary, or the “missing link” between fish and amphibians, would be discovered in 375 million year old rocks, between the two time periods. The rocks examined were sedimentary in composition, as the gradual and relatively gentle formation of sedimentary rock under conditions of mild pressure and low heat are conducive to the fossilization of animal remains. Sedimentary rock is also often formed in rivers and seas, where animals are likely to live. This site provides a resource that describes means by which fossils are formed and how the fossil record may be interpreted, and shows some examples of fossils demonstrating evolution through geological periods: http://www.fossilmuseum.net/fossilrecord.htm. In 2004, Shubin and his colleagues were looking for fossils on Ellesmere Island, in northern Canada. This location was chosen because of its lack of human development, as well as of obstructing natural formations and life forms such as trees, which

These Paleozoic rocks are steeply plunging sandstones and siltstones, with a little event of limestone at Lilydale - the Early Devonian Lilydale Limestone. The Silurian rocks were stored in profound water, while the Devonian rocks, which are exceptionally fossiliferous, appear to have been stored in shallower water. These Silurian and Devonian rocks were folded into a progression of anticlines

Although the Ediacaran period was well before the first appearance of dinosaurs it shows that there were fossils many years ago. When dinosaurs first appeared things had changed there was still shallow water which meant that bones could be fossilized.

One piece of this history is the subsurface Paleozoic rocks. Paleozoic rocks are for the most part hidden in the Park despite being in the Colorado Plateau, which is likely due to both erosion, and it being buried in other various rocks. Next is the deposition of the Moenkopi Formation during the early Triassic time period. When North America was still apart of Pangea, the area that was the Colorado Plateau was located within close range of the Equator. 300-600 feet of sand and mud were accumulated during this time, with marine life being included which tells Geologists that the sea sometimes was in the area. The climate at the time was warm, with varying times of humid and dry spells. There is very few beds of the Moenkopi Formation left in the area once again due to erosion. Third is the deposition of the Shinarump Member of the Chinle Formation. This basal conglomerate was deposited on top of the Moenkopi Formation. It is made up of gravel and sand, which indicates that there was water depositing it. The Shinarump Member also averages between 35-50 feet thick. Next in the geological history is the deposition of Chinle beds later in the Triassic time period. When the sea regressed to the west of the area, a large plain was left behind. As the climate changed, so did the environment. Soon grasslands and marshes began to form in the area. During this time hundreds of feet of shaly material accumulated which formed both the Lower Petrified Forest Member and the Upper Petrified Forest Member. In some parts, these two members are separated by the Sonsela Sandstone Member, composed of the most petrified wood compared to all other rock units featured in the Park. The Owl Rock Member is at the top of the Chinle Formation, and completes it. Near the end of the Triassic time period, tectonic activity was occurring heavily in the Arizona basin. In the western sea at this time a chain of volcanoes erupted,

These techniques led to the discovery of the boundary between the two eras. A single thin layer of clay found within predominantly limestone rocks established this. By comparing the marine life found in, above, and below the clay, the marine life, like the dinosaurs, had been terribly affected by the extinction event. The percentage of life in the upper layers was dramatically lower than that in the lower. This was far more compelling than what was suggested by dinosaur’s fossils.

My outside source for questions 3 and 4 is a journal by Pat Shipman titled Fossils. This journal was published in The New Scientist Vol. 215, Issue 2876, p. 8-16.

“A minority disputes this theory, arguing that other events-such as volcanic eruptions, sea-level changes or a series of impacts-were to blame for the spectacular loss of species that occurred at the transition between the Cretaceous and Tertiary periods…”

: Fossils are the remains or traces of ancient organisms which have been preserved. For example, a fossil can exist as skeletal remains or even as a footprint. Such organisms are subjected to a slow rate of decaying since they have been rapidly buried under conditions that facilitate this. It is common for fossils to occur as hard-bodied organisms as these are more resistant to environmental influences. Fossils are usually found embedded in rock. The layers of rock are of different age and makeup. Hence fossils found in one layer would vary in characteristics from those found in another layer. They can be observed and analyzed through visual as well as radiometric means so that the age and morphology can be determined. These features indicate

Charophytes are green algae that have been found in fresh water to moderately brackish water environments. Their gyrogonites are minute oval or round calcareous bodies that represent the calcified parts of the oogonium i. e. the female reproductive organs. Most of the plant consists of organic matter that decays shortly after death. Under some circumstances the stems and branches of the plant become calcified and are also preserved in the geologic record. In the absence of the planktonic and benthonic foraminifers, ostracodes and charophytes becomes valuable biostratigraphic tool for geologic analysis and interpretation (Carbonel, 1988; Colin & Lethiers, 1988; Martin-Closas & Schudack, 1996, Schudack, 2000 & 2006). Moreover the charophytes have been the focus of intensive work since the early 1960, since it was hope to obtain valuable information on the dating, biostratigraphic and paleoecology of the strata (Schudack, 2002 & 2004). The present study attempts a comprehensive biostratigraphic evolution of the Late Jurassic – Early Cretaceous sequence at Messak escarpment based on the stratigraphic distribution of the charophytes species as this type of microfossils have not been studied before in Libya as well as the study area has never been studied for charophytes beforehand. On the basis of the stratigraphic distribution of charophytes it is possible to subdivide the Late Jurassic – Early Cretaceous sequence into four assemblage zones. These are described in ascending