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SEISMIC DATA
WGI specializes in the acquisition and interpretation of near-surface seismic reflection data. We have been focusing on data acquisition/interpretation of continental deposits. Recent projects include the delineation of paleovalleys that contain Cenozoic Florissant Formation strata in the Florissant Fossil Beds National Monument, Colorado, and the Rocker Operable Unit, Rocker, Montana. Florissant Fossil Beds National Monument ProjectAbstractSEISMIC REFRACTION AND REFLECTION SURVEYS OF THE LATE PALEOGENE FLORISSANT FORMATION, FLORISSANT FOSSIL BEDS NATIONAL MONUMENT, COLORADO Shallow seismic refraction and reflection surveys were done over several areas within Florissant Fossil Beds National Monument (FFBNM). The refraction surveys included lines located in the southeastern part of the FFBNM, in the region crossed by the Lower Twin Rock Road, and a refraction line placed within the Petrified Forest area. The reflection surveys were done in the eastern part of the FFBNM, near Barksdale Campground, and in the southwestern part of the FFBNM, near the Monument's Visitor Center.Analysis of refraction data acquired from both the Lower Twin Rock Road and Petrified Forest areas indicates that there are three velocity layers present. The upper two velocity layers range from 571 meters/second to 1798 meters/second and are interpreted to represent the Florissant Formation and the water table. The third velocity layer ranges from 2525 meters/second to 2943 meters/second and is interpreted as bedrock. Refraction data from the Lower Twin Rock Road surveys show that a Tertiary paleovalley exists south of the current Grape Creek valley. In contrast, Tertiary fill along the Petrified Forest line thickens toward Grape Creek.Analysis of reflection data from the southwestern part of the FFBNM indicates that the Florissant Formation onlaps bedrock, and that its thickness increases in the direction of Grape Creek. Reflection data from the Barksdale Campground area suggest that a Tertiary paleovalley is situated to the east of the present stream valley of Grape Creek.(Abstract, Geol. Society of America National Meeting, Denver, Colorado, 1996, by Hanneman, D. L., WIDEMAN, C.J., and Evanoff, E.)
This line is an east-west line shot across a tributary valley approximately 1 mile east of the main Florissant valley. Yellow color indicates Tertiary Florissant Formation; red color covers the top of basement. R1 is interpreted as the basin-fill/basement interface.
Rocker, Montana Project
Seismic reflection data from Rocker Site. Time given is two-way, and is in milliseconds. Note bright reflector at approximately 210 ms; this is interface between Tertiary fill and basement.
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