Description for file +quot;footprints.gif+quot; 769 X 1308 pixels, 1 bitplane. Part of fig

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From: (R. Andrew MacRae) ------ Description for file "footprints.gif" 769 X 1308 pixels, 1 bitplane. Part of figure 88 of Balsley, 1980. Balsley, John K., 1980. Cretaceous wave-dominated delta systems: Book Cliffs, east central Utah: a field guide. Unpublished. Amoco Production Company, Denver Coldorado, p.1-163. [Although unpublished, this book is a classic available in most univerisity geology libraries.] This is a map of the roof (top surface) of a coal seam in an abandoned mine located in late Cretaceous rocks of the Blackhawk Formation, near Price, southeastern Utah. This is but one of many similar occurrences in the area. Many local miners have footprints as doorstops :-), or you can view specimens in the Price museum (highly recommended). The scale (15 feet) is located at the bottom of the image. The large, black rectangular areas are "pillars" of coal left to support the roof (I filled them with black so the image would compress better). The seam has the coalified stumps of trees (the black, radiating symbols) growing on the coal surface (then peat), fallen logs and branches (the elongate rectangular, outlined symbols ), and numerous dinosaur tracks of several species (the 3-lobed, black symbols). The shape and size of the three symbols approximates their real appearance (photos also in Balsley). Balsley provides the following description of these and other features of the sediments within and on top of the coal seam (p. 133): "Stands of large trees and palm thickets have been preserved in growth position. Root systems of the larger trees extend horizontally across the peat surface and show development of the northwest-southwest orientation discussed earlier [this is perpendicular the regional paleoshoreline]. Where roof falls have occurred, the vitrianized [coalified] tree trunks are commonly exposed in cross section. .... The spacings of the trees are similar to the spacings of Cypress trees in Okefenokee Swamp. Here, tree spacings are determined by crown widths. Occasionally, leaf floras are preserved on the basal surfaces of the flood deposits [on top of the coal seam - he is talking about _river_ floods :-)]. The leaf assemblages are commonly dominated by broad-leaf angiosperm genera with a scattering of palms, conifers, and ferns... Charcoal in the coals suggests that during the dry seasons, fires swept through the swamps as they do in modern Okefenokee..... In the swamp forests, the peat surfaces have been deformed by vast numbers of dinosaur footprints [some of which he illustrates as photographs]. The footprints are depressions in the swamp peats that have been filled with flood-deposited sediment..... Peat is a water-saturated material that after compression tends to rebound to its undisturbed state. The abundance of well-defined tracks suggests that they were made just prior to the deposition of the sediment and that dinosaurs were very abundant in the swamp forests... Occasionally, tracks of three-toed dinosaurs [probably hadrosaurs], occur around the bases of the trees, and are pointed inward as though the animals were browsing on the standing vegetation. The large numbers of well-defined, three-toed tracks and their association with trees suggest that the parent dinosaurs were gregarious herbivores. Occasionally, single trackways can be followed for considerable distances in mine entries driven parallel to the paths of the dinosaurs." Once creation "scientists" finish explaining this section, they can start on the rest of the book :-)


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