Labels:text | screenshot | font | printing | black and white | letter | number | document OCR: Tectonic, stratigraphic, and sedimentologic significance of a regional discontinuity in the upper Judith River Group (Belly River Wedge) of southern Alberta, Saskatchewan and northern Montana. "Say What?" Dr. DavidA. Eberth, Royal Tyrrell Museum of Palaeontology Dr. Anthony P, Hamblin, Geological Survey of Canada This is a recent scientific paper of Dr. David Eberth, Curator of Sedimentary Geology at the Royal Tyrrell Museum, and colleague Dr. Tony Hamblin, published in the Canadian Journal of Earth Sciences. Below Dr. Eberth explains some of the content and significance of the paper. In 1987, I noticed subtle differences between the upper and lower layers of rock exposed in Dinosaur Provincial Park, north of Brooks. The upper layers are grey and contain thick beds of sandstone, whereas the lower layers are yellow and contain thin beds of sandstone. Furthermore, I noticed that of the 300 articulated dinosaurs that had been collected from Dinosaur Park during the last 80 years almost all had come from the upper grey layers, Adams Saw & Sales As expected, the lower layers were deposited earlier in time, about 77-76 Air Canada million years ago. I concluded that these lower layers are the remains of Alberta Marble & Tile Ltd shallow, fast-moving, braided rivers (wide, shallow and sandy) that originated Alberta Power Ltd in north-west Montana and flowed to the northeast. In contrast, the upper Archer Resources Ltd layers (76-74 million years old) were deposited by deep, meandering rivers Badlands Taxi that originated in eastern British Columbia and flowed to the southeast. Thus, Canadian Utilities Ltd there was a significant change in the style and direction of river flow in Ou Corporate Edge southern Alberta about 76 million years ago. Why? Further study showed that the change in the river systems resulted from Centennial Air changes in the way that the Rocky Mountains were forming. Over millions of Chateau Lake Louise years, differences in rates and intensity of mountain building in different parts Code Hunter, Barristers & of British Columbia controlled the amount of sediment released from the Solicitors mountains, and the slope of the plains across which the rivers flowed. About D.W. Axford & Associates 76 million years ago, a very pronounced uplift in south-eastern British Drumheller Inn Columbia caused southern Alberta to sag. In response, rivers from the north Elk's B.P.O.E. began flowing down-slope toward the sag Fording Coal Limited Really fascinating, however, is the fact that fossil dinosaur skeletons are Gulf Canada Resources abundant in the upper layers (the meandering river deposits) and almost Ltd totally absent in the lower layers (braided river deposits). Our study revealed Hi-Way 9 Express Ltd Hotel MacDonald that dinosaurs were probably equally abundant in both ancient IGA Drumheller environments, but because the ancient meandering rivers were deep and International Colin Energy floored by very large sand dunes, dinosaur carcasses having found their way into these rivers were more likely to be completely buried and, ultimately, Corp preserved. Dinosaurs skeletons are extremely rare in the lower layers because Ocelot Energy Inc Pacific Western Tours the ancient rivers in which these layers were deposited were shallow and Priority Printing Limited flowed intermittently, Thus, this study offers a partial answer to the question, Rosebud Theatre why are dinosaur skeletons so abundant in southern Alberta? Our study shows Royal Tyrrell Museum fossils of dinosaur skeletons are abundant here because conditions for burial and preservation were particularly favourable. Secondly, burial conditions were favourable because uplift of the Rocky Mountains caused southern Alberta to sag, which in turn partly initiated the formation of deep meandering rivers in which carcasses could be more easily preserved. This paper is one step in understanding the history of Alberta's ever-changing environments and the reasons why Alberta is a unique treasure trove of dinosaurs,
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