RELOCATING “HAYDEN” ANTEBELLUM POWDER RIVER BASIN PALEOGENE CONTINENTAL LOCALITIES – A SED/STRAT CLASS EXERCISE
The classroom exercise is divided into field and lab observations. The two available USNM 1972 (L2175) samples weighing 163 and 49 g, respectively (Block 1, 2). The blocks vary in value and chroma with a hue of 10YR (shells – pale yellowish brown, grayish orange, very pale orange, dark yellowish orange; fresh matrix – grayish orange; weathered matrix – pale yellowish brown, moderate yellowish brown, dark yellowish brown). Fresh sediment is slightly HCl-reactive on fresh grains and less so reactive on iron-impregnated weathered surfaces. Hand sample observation: Relatively well-lithified, iron-stained, fossiliferous, subangular, moderately sorted, slightly calcareous, fine-grained quartz sandstone. Gains observed and measured under microscope confirm “field” observations. A silty fine-grained sandstone was derived by Ro-Tap. An SEM elemental analysis indicates the abundance of quartz, with goethite, calcite, and minor percentage clays (e.g., illite). The next step is for students to examine (this summer) outcrops along Clear Creek near Buffalo, Wyoming, in search of a fossiliferous, fairly resistant channelform sandstone as described.