Page:Field Notes of Junius Henderson, Notebook 1.djvu/111

 lower deposits showed origin similar to the river deposits. The pebbles and small boulders contained in these river deposits as well as in the loessoid were usually rounded, with some flattish surfaces and sometimes angular, suggesting transportation some distance at a time by strong floods without much wear, as often occurs nowadays. The pebbles left on the surface by wind erosion are of quartz, hornblende rock, andesite etc. – mountain debris. Throughout this plains region erosion and deposition have frequently progressed with terrific rapidity during great storms. Prof. Cannon showed me one place where a gulch about 50 ft. in depth was cut through the loessoid and river deposits, to bedrock (Denver sandstone), by a single storm NE of. At brick kiln in S bluff of we visited place from which Cannon, Bethel and Marvin