Heading west, the Plains rise
gradually to reach an elevation of 6,000 feet near their terminus at the eastern foothills of the Rockies.
The major features of the Eastern Plains include the two shallow river valleys of
the Arkansas and the South Platte and the large flat divides of rolling grassland between and to
either side of the valleys.
Sources:
George, Russel D., Geology and Natural Resources of Colorado, Boulder, CO, University of Colorado, 1927.
Guide to the Geology of Colorado, ed. Weiner, Robert J. and Haun, John D., Geological Society of America, 1960.
Pearl, Richard Maxwell. Exploring Rocks, Minerals, and Fossils in Colorado, Chicago, Sage Books, 1969.
