The Relationship Between Taphonomy On Shell Stable Isotope Records

Approximately 17 meters thick, Unit A defines the lowest third of the Juniata Formation. Fragments of marine fossils, including bryozoans, brachiopods, and gastropods, are commonly found in the bottom-most portion of this unit of structureless mudstone and quartz arenite. Quartz grains in the sandstone beds of Unit A are typically immature and fine-grained, though the sandstone packages tend to coarsen upwards. Though typically structureless, intermittent bedding of the sandstone and shale packages is observed in this unit, and some areas display

It can be argued by some geologists that significantly more time is lost at bedding planes than is recorded by the accumulation of sediment and its later lithification into a sedimentary rock. In the present paper, the continuity of the sedimentary record is investigated. It is hypothesized that sedimentary strata preserved predominately records episodic sedimentation events and gaps represented by bedding planes symbolize more time than the preserved strata. The incompleteness of the geologic record and the role of rare events was studied using data gathered from a variety of sedimentary outcrops and cores. The author addressed his hypothesis using this collected data in terms of sediment preservation and represented preservation as a function of two modes of geomorphic processes: Magnitude and frequency. The author tested his hypothesis using relatively modern storm events to represent sedimentation, showing how daily processes can distort the geologic record, and by using ancient examples to illustrate how some storms can be preserved in spectacular condition.

The author and his colleagues specifically chose to focus on 375 million year old rocks in their search for fossils because this was the time frame that provided fish that would be useful to study from. The 385 million year old rocks provided fish that look too similar to the ones we have now and the 365 million year old rocks have fossils that don’t resemble fish. The 375 million year old rocks, however, provide fossils that show the transition between fish and land living animals.

Complete this week’s lab by filling in your responses to the questions from Geoscience Laboratory. Select answers are provided for you in red font to assist you with your lab work. Although you are only required to respond to the questions in this worksheet, you are encouraged to answer others from the text on your own.

The aim of this lab is to determine if the Seven River oyster is suitable for oyster restoration. During this lab we learned that Salinity affects the oysters if it is more than 10-13ppt. We also have knowledge that there is a parasite (the protozoan, Haplospordium nelson) that causes the disease MSX in oysters (Readel, 2000). Moreover, at the lab we knew that MSX bacteria will grow if salinity is above 15 ppt that will cause the oysters to die. The oysters can be affected by MSX if the salinity is above 15 ppt (Readel, 2000). Furthermore, Oysters are also used to filter the water of the river. Also, we learned that the range of tolerance of salinity for oysters is 10-27

The 440 million year old Georgian Bay Formation is largely composed of fossiliferous grey-black shale (L1R). It also consists grey fine-grained limestone, sandstone and green/grey siltstone interbedded with green/grey and blue/grey shales (Bond et. al. 1976). The frequency of hard rock units increases toward the top of the formation. Recurrent tropical storms across the Ordovician seas caused the formation of shady, thin limestone with wave ripples on top. Numerous fossils can be found in the siltstones and limestone including molluscs, crinoids and gastropods

At Disaster Beach, a refuse pile was discovered containing shellfish remains. The pile most likely came to be because of Cardium Sp., which was located two-hundred yards inland from the high tide line. The inland did not have a complete rainforest to support the semi-sedentary system, but there were eucalyptus plants that helped. The high points were the only logical place with grain processing and potential religious activity like having a Shaman look over the sites. However, the high points did not have any detectable stratigraphy when they were studied. Carbon dating of three shell samples, in three separate units was taken, and then returned. The shell fragments found on Disaster Beach were dated at the

British Colombia in Canada, much like California in the United States, used to be a shallow sea and home to much sea life and is now home to thousands of marine animal fossils. For this reason it is believed that Dinosaur Provincial Park consisted of a lot of sands and muds that are characteristic of costal plains (Sues, Henderson, & Tanke, 2010, pg. 1292). When Sues, Henderson, and Tanke (2010) where going about measuring fossil shifts and the amount of fossils that have been lost they took into account the amount of soil that erodes away every year, the vertical and horizontal distribution fossils found within the park, and large landmarks such as rivers and glaciers that could effect fossils in the area (pg.1293). Accounting for these factors

The base of IIIb1 appears slightly oxidized and yielded an age of 2277± 36 14C yr BP. Above this is a ~60-cm-thick, organic-rich “black mat” (IIIb2) consisting of multiple thin beds containing varying amounts of plant matter including both decomposed humic material and uncharred plant macrofossils that constitute a significant proportion of the sediment volume in the most organic-rich deposits. The IIIb2 black mat was formed between 1934 ± 29 14C yr BP and 1759 ± 25 14C yr BP, with the most organic-rich portion predating 1833 ± 36 14C yr BP. Organic carbon content of the black mat varies, but the highest values are ~2%. Plant remains in IIIb2, consisting mostly of bulrush achenes and pollen, indicate emergent aquatic floodplain vegetation, and the unidentifiable stem fragments ubiquitous throughout the layer are likely also bulrush (Figure 8). Faunal remains within IIIb2 at 11-37 include snail and ostracode species indicative of marshy conditions (Table 4). From the base of IIIb1 to the sharp upper boundary of the IIIb2 black mat, a trend of decreasing calcium carbonate, increasing gypsum, and increasing organic carbon is evident. Gypsum content ranged from 3.7–16.6% and occurred as tiny clumps of intergrown lathe crystals, whereas carbonate content ranged from ~4–13% and occurred as small soft

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

Isotopic profiles of mollusks provide insight to the biology of fossil and living specimen and the conditions under which they live in. Isotopic profiles record seasonal variance in temperature, salinity, dissolved oxygen concentrations and can provide evidence of changes in bio mineralization in correlation with seasonality and ontology. The shells of Tridacna are beneficial for Pleistocene paleoceanography isotopic studies because of their large size making it easier to gain detailed samples of shell carbonate. The density of the shell better preserves original carbonate of the shell.

A variety of chemical and physical processes change an organism after its death. Taphonomy is the study of these processes and how they are influenced by the activity of humans, animals, and natural agents (Erfemov 1940, Behrensmeyer 2000, Duday 2009, Nawrocki 1995, Stodder 2008:71). Taphonomy is especially important to bioarcheologists because it enables them to reconstruct how mortuary environments affect skeletal remains. Furthermore, there are two main types of taphonomic factors, extrinsic and intrinsic that are analyzed. Extrinsic taphonomic elements represent as the surrounding environmental influences that affect the decomposition of remains. Examples of extrinsic elements include weathering, human disturbance, and plant roots. Intrinsic

Analyzing the change in species over time utilizes the support from many disciplines of science in order to come to the most plausible explanation of said change. Geology more specifically, the fossil record is one such discipline that elicits profound insight on speciation. The fossil record is best described as life’s evolutionary story as it clearly shows sequential change in organisms throughout time by providing a starting point and in many cases transitional fossils as benchmarks for comparison. Sedimentary rock is crucial to this process as it is what cements organisms in time at their time of death. Sedimentary rock is common on Earth and formed by the weathering of older rocks. As this weathering occurs organisms that have died are buried in the sediments produced and preserved as

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.

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.