A Multi-proxy Reconstruction of the Late Quaternary Site at Deeping St. James, Lincolnshire - Coursework Example

A Multi-proxy Reconstruction of the Late Quaternary Site at Deeping St. James, Lincolnshire DeepingSt. James is a former pond in very close proximity to the modern River Welland. However, it formed after the abandoning of a channel by the river during the ipswichian interglacial. Often climate change attributes to the changes of river behavior. The ipswichian interglacial presented temperatures that were higher than the norm in the British region. After the river abandoned its former channel, deposition started. Previous proxies have dated the event to over 120000 years ago. Through the analysis of the ecology that thrives in the region, one can distinctly identify the environmental conditions of the time. Although different proxies have analyzed different aspects of the ecology, this paper will highlight the analysis of different types of mollusca extracted from a sentiment sample from Deeping St. James. Through the identification and description of the mollsuca in the sentiment, the paper will present a reconstruction of the environment of the pond and describe the environmental conditions of the time. Introduction Climate change accounts for the conditions evident geographically today. Archeologists have ventured into describing the probable processes and stages that resulted to the current environment. As environmental changes occur, a shift in the organisms that can thrive in certain ecological conditions occurs. Understanding the past environment can help in putting the current environment into perspective. Deeping St. James in Lincolnshire is one of the characteristic sites that that contains evidence of the climatic changes over time leading to the deposition of different materials. Climatic changes in the region have comprised periods of temperate conditions followed by extremely cold conditions. Different researchers have studies the palaeo-environment and produced different proxies that can suffice in providing information concerning the site over time (Haslett, 2002:1-2). A multi-proxy analysis approach is one of the critical ways in providing relevant information while reconstructing the past environment. The primary concern in Deeping St. James would was being able to analyze the different species of mollusks thriving in the environment today. A morphological and ecological definition of the species would shed light into the nature of past environment. This paper will analyze the species and provide a sketch of the reconstruction of the site during the ipswichian stage. The reconstruction of the palaeo-environment process begins with an analysis of the stratigraphy at Deeping ST. James in order to establish the geological framework of the site (Haslett, 2002:1-2). A thorough analysis of the available proxy records is essential in providing the basic palaeo-environment. The third and most critical step involves the development of a chronology of events that can help construct a dating framework. The next step involves the linking of different sequences using a correlation basis with data from other locations. Finally, a consideration of all lines of evidence helps in the synthesis of palaeo-environment. Methods In order to identify the mollusc species that thrives in the sediments at Deeping St. James Lincolnshire, there was a sample for analysis. The methods of analysis used depended on the sample and organism of interest. The source of the sample was the site of interest. The initial procedure involved an extraction of the organisms provided. After extraction, the available proxies and reference books served as resourceful materials in the identification of the extracted species, moreover, these materials provided information concerning the ecology of the species. The final procedure involved the development of a reconstruct of the palaeo-environment of the site. Procedure of Extraction The initial step involved sprinkling of a thin and even covering of the sample onto a petri-dish. The following step involved picking out all the shells belonging to snails from the sample into a partitioned petri-dish using a paintbrush (Horne, Holmes, Viehberg, & Rodriguez-Lazaro, 2012:305). For ease of identification, a critical analysis of the shells followed. A differentiation process based on size and morphology proved to be very important in distinctly identifying the different species. In addition to the size of the shell, the shape and of the aperture, absence or presence of teeth in the aperture and growth lines were other factors considered in the identification process. All the shells exhibiting similarities ended up into the same compartment. With the use of the provided diagrams, it became possible to identify the species of mollusca from the sample. After identification, calculation of the relative abundance followed. Results After analysis of the sample provided, there was evidence of the following species. There were different numbers of the species. Discussion Species Habitat Theodoxus fluviatilis Fresh Water Valvata piscinalis Fresh water-Moving Bithynia tentaculata Fresh water-Moving Vallonia Land Mollusca Lymnaea palustris Fresh Water- catholic Lymnaea peregra Fresh Water- catholic Table showing the habitats of the Mollusca species Theodoxus fluviatilis In the sample sediment, there was evidence of Theodoxus fluviatilis, whose common name is the river nerite. This species has unique characteristics. The organism exhibits a high preference for brackish water, symbolized by the mixing of fresh and salty water. This translates to the fact that the organism has a high adaptability to salty conditions because it must learn how to utilize salty water emanating from the sea. This special adaptation requires a high energy level. Therefore, the morphology of the shells consists of a thin shell. However, other species living on land and in fresh water exhibit a different morphology (Allison, & Bottjer, 2011:87). The subspecies that lives in fresh water has a thick but half-oval shell. The whorls of the shell often expand at a first rate to attain the maximum diameter of the aperture. With their advancing in age, the shell of the common river nerites melts down. This makes the identification process quite difficult. Moreover, the shells have a variety of stripe patterns and accurate identification becomes possible on consideration of the operculum characteristics. The species has a unique shell lid. Fresh water nerites prefer areas that have a relatively hard underground but with a large body of flowing water. Such a habitat allows the nerite to survive on diatoms. In order to utilize the silica contents, the nerites often have to crush it against the ground. Bithynia tentaculata This species is common in different continents and has an oval or conical shell. The shell is yellowish in color and on it are blackish and brownish coverage of algae. The whorls of the algae have a slight rounding and a clear separation of suture. The operculum ends in an angular corner at the upper side, and this is critical in identification of the species. Its body has both black and brown colors with some, having orange spots. It has a noticeable proboscis-like snout but a tiny head (Allison, & Bottjer, 2011:76). The length and pointed nature of the tentacle also defines the common Bithynia. Its main food comprises decaying material and food particles that it manages to filter from the water. It prefers to live in either stagnant ore moving water. The depth of its habitat in water may vary but it seldom lives beyond the depth of 15 meters. The species exhibits a preference for waters that have dense vegetation, and muddy ground. Moreover, high levels of oxygen and calcium carbonate are a necessity to the species. In waters with a fast streaming rate, the common Bithynia adheres to the lee side where it meets a little calmness and experiences minimal water waves. This species presents a high level of adaptability especially in unfavorable conditions such as varying pH values, sodium and potassium concentrations, and minimal oxygen supply. Moreover, it tolerance also becomes evident in saline conditions, and this means that it can tolerate brackish waters. As long as the habitat presents the common Bithynia tentaculata with favorable conditions, the snail can live for a period of three years. Valvata piscinalis This species has a shell that differs from the rest because its aperture appears pinched but with a spire exhibiting attenuation. The height of the spire increases in proportion to the increase of the eutrophic conditions. The shells of these species have four to five whorls with the color varying from white to beige. However, toward the apices, the color changes to the ranges of red to orange. The operculum in this species has spiral markings of approximately 10 turns that begin from the central point. The valvatids of this species are often yellow in color with grey and white spots and blue eyes. However, the mantle, snout and penis base appear to have a darker pigmentation than the rest of the body parts. The organisms in this species exhibit a bipectinate ctenidium serving as the respiratory organ. This organ is large, with its size making it highly visible. The organisms found in Europe are usually 7mm in height and 6.5mm in width although they appear smaller. These valvatids can survive comfortably in both stagnant and moving water. Therefore, common habitats include creeks, ditches, rivers, canals, reservoirs, and lakes. The organisms exhibit a preference for sand, silt and rely on detritus and diatoms for nourishment. Similar to other species, these organisms can exhibit a high level of tolerance with environmental conditions, high growth rates, and fecundity in high levels. Moreover the spawning rate is fast and happens twice or thrice each year. The organism can live beyond three years with sexual maturity occurring after the first year. Vallonia Species In order to identify these species correctly, shell shape and whorl arrangement was very critical. Vallonia consists of small land mollusca that breathe in air. These are the terrestrial pulmonate gastropods (Horne, Holmes, Viehberg, & Rodriguez-Lazaro, 2012:84). Although subspecies differ greatly, the genus has organisms whose shells are about 3mm in width and 1.8mm in height. In addition, the shells of this genus exhibit a wide range of umbilication with whorls varying from three to four and half. These species thrive on land preferably under trees. Others may prefer damp land that is in close proximity to ponds and rivers. Moreover, a few organisms in this genus exhibit adaptations for rocky places as well as cold places. Lymnaea peregra There are two subspecies in this category of mollusca (Taylor, & Lewis, 2005:82). One of the categories thrives in fresh moving water while the other prefers fresh but stagnant water. Although both subspecies have similarities, they present morphological differences determined by their preferred habitat. The organisms that prefer moving water exhibit a greater ration of aperture length to shell length. Those preferring the lentic sites have a smaller ratio in this parameter. Studies have speculated that the bigger apertures in organisms living in lotic sites could be an adaptation for surviving in running water. Lymnaea palustris There was evidence that this species existed because of the cone-shaped shells that were brown in the sample. Moreover, the shells of these organisms are either medium-sized or large with whorls of moderate convexes and characteristically flat sutures (Taylor, & Lewis, 2005:83). Moreover, they appeared to possess quadrate plates and small apertures, with closed umbilicus. These organisms prefer fresh to live in fresh waters but usually at the flooded ends of large bodies of water. Sometimes, they occur at the shallower ends of the water. They also exhibit a high adaptability of being amphibious in seasons when water dries up. Green Beetle insect This insect occurs in areas where there is a wide variety of trees producing fruits such as berries, grapes, pitches, apricot, and maple. Usually, they notice the over-ripening fruits, and find temporary abode inside the fruit for sometime. In morphology, the insect appears bigger than closely related species with a dark brownish body exhibiting green stripes. Other organisms are completely green, but presenting brown margins. The defined morphology eased the identification process. Potamogeton seed This seed present in the sample indicated the existence of the Potemotegon pondweed that thrives in brackish, alkaline, and fresh water lakes. The aquatic plant exhibits rhizomatous network of roots. During unfavorable conditions, the rhizomes transform into resting buds. These buds often sprout during the next favorable season. Stems of this pondweed have either a reddish brown color or beige, and the plant may have multiple stems with many leaves. The fruit of this pondweed undergoes several changes during fossilization leaving the endocarp. The dimensions of the endocarp may vary but are very critical in the process of diagnosis and reconstruction of the past. The seed identified was in the range of 1.49mm and 1.85mm in a size characterized by a massive beak of a triangle shape. The beak was of moderate dimensions and measured approximately 0.55 mm width and 0.86 lengths. Moreover, the fact that the lid was wavy with a smooth ending and the arm present on the plane served to ascertain that the seed from the sample belonged to the pondweed. Hawthorn seed The presence of this seed in the sample presents evidence of the existence of the hawthorn tree. In most of the regions where it grows, the tree has a significant use as a hedgerow. The tree grows in temperate regions with sunny sessions. Its fruits are berry-like and the size of an apple with a single seed. In other areas, the trees serve as frost-resistant roots during frosty weather. The fact that the seed probably had its way through the intestines explains its morphology. Taphonomy Changes in Mollusca Accessed from http://molluscs.at/gastropoda/index.html?/gastropoda/freshwater.html Diagram showing the shells of different species after fossilization The fossils of different species of mollusca often undergo several changes during the fossilization period. The gastropoda shells belonging to the terrestrial snails often undergo fossilization but remain as closed systems in most cases. This highlights the fact that after decomposition of the flesh and body, the shell survives with minimal carbon content alterations over time. Although the shape of the shell may have changes, it can survive to recognizable status over a long period. This explains why the sample contained shells of land mollusca identified and described above. The shells differed greatly from those of the live species because over time, dissolution took place altering the shape and size. Dissolution results when shells in a site encounter acidic rainwater (Allison, & Bottjer, 2011:34). Moreover, other physical and chemical procedures affect mollusca fossils changing them. Different shells often undergo varying mechanical and chemical changes over time. The seeds of different trees also change in dimensions during fossilization. The changes in weight serve as a significant factor in developing dating records. A good example is that of the pondweed seed that reduces in weight over time. Comparison with the actual weight of the seed can present a researcher with reliable information concerning its age (Taylor, & Lewis, 2005:73). Moreover, taphonomical changes are critical in determining climate changes that may have taken place over time. Climate changes have the potential of altering the dissolution processes of the fossils. Reconstruction of the Environment Most of the mollusca extracted from the sample are fresh water species, signifying that the present of a body of water. Some of the species only thrive in moving water. With the presence of species highly adapted to flourishing in running water through their large feet indicated by large apertures, it becomes evident that the river torrents were once fast flowing. Over time, climatical changes may have taken toll of the river forcing it to shift its channel. The abandoned channel likely developed into a pond because of the presence of the aquatic pondweed. Moreover, the presences of mollusca species that survive in stagnant waters serve to augment the possibility of the formation of a pond. Terrestrial species with the preference of living on damp areas found in the sample serve as more evidence that the region had a water body (Haslett, 2002:57). The presence of nerites in the sample with the adaptability to salinity shows the aftermath of the water body as climate conditions changed over time. Moreover, the presence of the green insect signifies an additional feature of the environment. This is because these beetles feast on a variety of fruits indicating presence of trees surrounding the water body. The presence of terrestrial mollusca species that can thrive in shaded areas also translates to the presence of large trees in the environment. The hawthorn seed present in the sample is evidence of a temperate climate because the tree thrives in temperate ecologies. Its purpose as frost-resistant tree translates to an additional feature of temperate regions. Since it flowers during sunny summers, it serves as evidence that Lincolnshire once had higher temperatures. In addition, it confirms the existence of the ipswichian stage marked by the interglacial deposits. As described above, mollusac species analyzed indicate the presene of river terraces, which are a characteristic of the ipswichian period. the fact that the sample contained valvatids, organism that signify the presence of silt, sand and other forms of deposits suffices vas evidence of interglacial deposits. After the deposits, the formation of creeks, ditches, and terraces that are the common habitats of valvatids resulted. This leads to a confirmation that warm and cold climates existed in the region and are the reason why the geostratigraphic deposits occurred (Armstrong, & Brasier 2005:16). The presence of vallonia species with adaptability to cold areas supports the existence of cold climates in the devensian stage. Images showing how the climate changes took place during the Ipswichian Stage Accessed from http://www.qpg.geog.cam.ac.uk/research/projects/interglacialrivers/ Full Interglacial, accessed from http://www.qpg.geog.cam.ac.uk/research/projects/interglacialrivers/fphii.html Full Interglacial Sub Stage 2, accessed from http://www.qpg.geog.cam.ac.uk/research/projects/interglacialrivers/fphii.html Full Interglacial Sub Stages 2-3, accessed from http://www.qpg.geog.cam.ac.uk/research/projects/interglacialrivers/fphiii.html Late Interglacial, accessed from http://www.qpg.geog.cam.ac.uk/research/projects/interglacialrivers/fphiv.html Conclusion As described above, climate change accounts for the conditions evident geographically today. Environmental researchers have ventured into describing the probable processes and stages that resulted to the current environment. As environmental changes occur, a shift in the organisms that can thrive in certain ecological conditions occurs. Understanding the past environment can help in putting the current environment into perspective. Deeping St. James in Lincolnshire is one of the characteristic sites that that contains evidence of the climatic changes over time leading to the deposition of different materials. Climatic changes in the region have comprised periods of temperate conditions followed by extremely cold conditions. This study-involved extraction of mollusca species present in the sample provided, whose ecological analysis could present useful information concerning the past environment. The species described present evidence for the ipswichian stage that occurred in Britain. During that period, there were trees growing in areas next to the flowing rivers. Bibliography Allison, P. A., & Bottjer, D. J. 2011. Taphonomy: process and bias through time. Dordrecht, Springer. Armstrong, H., & Brasier, M. D. 2005. Microfossils. Malden, Mass, Blackwell. http://search.ebscohost.com/login.aspx?direct=true&scope=site&db=nlebk&db=nlabk&AN=132394. Haslett, S. K. 2002. Quaternary environmental micropalaeontology. London, Arnold [u.a.]. Horne, D., Holmes, J., Viehberg, F., & Rodriguez-Lazaro, J. 2012. Ostracoda as Proxies for Quaternary Climate Change. Oxford, Elsevier Science. http://msvu.eblib.com/patron/FullRecord.aspx?p=1095010. Taylor, P. D., & Lewis, D. N. 2005. Fossil invertebrates. Cambridge, Mass, Harvard University Press. Read More