Fringing coral reefs at Discovery Bay, Jamaica, exhibit a pronounced depth-related gradient in water turbulence and associated physicochemical taphonomic factors (abrasion, dissolution), and thus provide ideal settings for investigating the influence of taphonomic processes on the formation of fossil assemblages. Foraminifera are prominent constituents of bioclastic sediments at Discovery Bay, and exhibit a high diversity of test sizes, shapes, wall compositions, architectures, and microstructures which may potentially affect their post-mortem behavior. We have developed a taphofacies model for Jamaican north coast fringing reefs and associated environments that has allowed us to generate hypotheses about the formation of foraminiferal sediment assemblages
Structure from motion (SfM) computer vision is a remote sensing method that is gaining popularity due to its simplicity and ability to accurately characterize site geometry in three dimensions (3D). While many researchers have demonstrated the potential for SfM to be used with unmanned aerial vehicles (UAVs) to model in 3D various geologic features, such as landslides, little is understood concerning how the selection of the UAV platform can affect the resolution and accuracy of the model. This study evaluates the resolution and accuracy of 3D point cloud models of a large landslide that occurred in 2013 near Page, Arizona, that were developed from various small UAV platform and camera configurations. Terrestrial laser scans were performed at the landslide and were used to establish a comparative baseline model. Results from the study indicate that point cloud resolution improved by more than 16% when using multi-rotor UAVs instead of fixed-wing UAVs. However, accuracy of the points in the point cloud model appear to be independent of the UAV platform, but depend principally on the selected camera and the image resolution. Additional practical guidance on flying various UAV platforms in challenging field conditions is provided for geologists and engineers.
Despite numerous distributional studies of foraminifera in modern shallow-water carbonate environments, information loss and taphonomic bias in the transition from life to death assemblages of foraminifera in these environments have not previously been examined in detail. Surface sediment and vegetation samples were collected along six nearshore traverses and one traverse across the back reef lagoon off Key Largo, Florida. Living foraminifera are found in abundance on algae and the marine angiosperm, Thalassia testudinum , while foraminifera in sediment assemblages are represented primarily by empty tests. Q-mode cluster analysis of living assemblages on Thalassia delineates inshore (depth 0.4–2.7 m) and offshore (3.0–9.0 m) back reef biofacies. Calcareous imperforate (suborder Miliolina) species thrive in quiet waters of the inshore biofacies, in which biotic interactions appear to be the prime factor in determining small-scale species distributions of living foraminifera. Fragile species are most susceptible to test destruction, and, therefore, sediment assemblages are dominated by more robust forms (e.g., Archaias angulatus, Valvulina oviedoiana , thick-walled species of Quinqueloculina ). Water turbulence primarily determines species composition of living populations of the offshore biofacies. These assemblages are dominated by the calcareous perforate (suborder Rotaliina) species Planorbulina acervalis and Rosalina bahamaensis . These species resist transport by encrusting Thalassia blades and having a test which fits flush with grass blades, respectively. However, sediment assemblages of the offshore biofacies are also dominated by typical inshore, robust species ( Archaias angulatus , thick-walled miliolids). Thus, inshore and offshore biofacies are not readily differentiated by Q-mode cluster analysis of sediment assemblages. Robust species are wide ranging and often abundant in sediment because of differential preservation and time-averaging of sediment assemblages. The resultant taphonomic bias may interfere with paleoecologic interpretations concerning intensity of water energy and distance from shore.
Taphonomy: A Process Approach is the first book to review the entire field of taphonomy, or the science of fossil preservation. It describes the formation of animal and plant fossils in marine and terrestrial settings and how this affects deciphering the ecology and extinction of past lifeforms and the environments in which they lived. The volume emphasises a process approach to taphonomy and reviews the taphonomic behaviour of all important taxa, plant and animal. It will be useful to anyone interested in the preservation of fossils and the formation of fossil assemblages, but it is aimed primarily at advanced students and professionals working in paleontology, stratigraphy, sedimentology, climate modeling and biogeochemistry.
Addressing the history of the earth in terms of geological process and the resolution of the fossil record, Ronald Martin presents a report on the current state of knowledge on a group of interconnected themes - process, scale and hierarchy, and the methodologies of historical sciences. He examines several questions about geological history: What is the evidence for processes that occur over long periods of geologic history? Why are these long term earth processes significant to the human race? How does one test hypotheses using the fossil record? And what, at the present rate of knowledge, are the limits of that record? As Martin explains, the project of the geologist is to interpret natural phenomena by integrating data into large contexts and constructing a historical narrative. Through the critical examination of these narratives, geologists can determine how the earth evolved into its present state. However, the scale employed in measurement can cause wide variations in the results of any inquiry into geologic process. Martin addresses a wide range of topics, including taphonomy, bioturbation, cycles of carbon dioxide, global cooling, and extinction. He supplements the theatrical framework with explanations of concepts and definitions of key terminology.
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