Assessment of the alluvial sediments in the Big Thompson River Valley, Colorado

Stratigraphy, lithology, and sedimentary features of Quaternary alluvial deposits of the South Platte River and some of its tributaries east of the Front Range, Colorado

“…No logs were found for alluvial fill of St. Vrain Creek and the Big and Little Thompson Rivers. Three sections through the alluvial fill of the Big Thompson River valley, constructed by S-wave seismic refraction methods, revealed one or, in some places, two gravel units (Barnett and Ellefsen, 2000). The maximum total thickness reported for alluvial fill in the Big Thompson River valley is 13 m. Two gravel units have also been recognized in the alluvial fill of St. Vrain Creek.…”

S-wave refraction survey of alluvial aggregate

“…For those situations where drilling causes problems, some of the needed geologic information may be obtained with a geophysical survey. Surveys of sediment deposits have involved many different geophysical methods, including airborne imagery (Singhroy and Barnett, 1984), airborne elec-tromagnetic profiling (Middleton, 1977), electrical resistivity sounding (Auton, 1992;Crimes and others, 1994;Jacobson, 1955;Middleton, 1977;Saarenketo and Maijala, 1994;Wilcox, 1944), frequency domain electromagnetic profiling (Auton, 1992;Middleton, 1977), P-wave refraction (Crimes and others, 1994;Middleton, 1977;Odum and Miller, 1988;Saarenketo and Maijala, 1994), S-wave refraction (Barnett and Ellefsen, 2000;Ellefsen and Barnett, 2001), and ground-penetrating radar (Jol and others, 1998;Saarenketo and Maijala, 1994). Moreover, electrical resistivity sounding, time domain electromagnetic sounding, frequency domain electromagnetic profiling, and ground-penetrating radar were compared by Ellefsen andothers (1998, 1999) to evaluate their suitability for characterizing sediments used for aggregate.…”

“…S-wave refraction is relatively new compared to other geophysical methods, and, consequently, it is used infrequently. Indeed, we believe that S-wave refraction has been used only once to characterize shallow sediments that could be mined for aggregate (Barnett and Ellefsen, 2000;Ellefsen and Barnett, 2001). This previous investigation was of a 9-km section of an alluvial valley with farms, ranches, and homes, and so the measurements were sparse.…”