The fluvial surfaces in the diagram occur slightly upstream from the contemporary confluence of the Laramie River and the Little Laramie River. The surfaces 3b, 4, 5, and 6 were probably deposited by the Laramie River, while surfaces 1, 2, and 3a were probably deposited by tributaries of the early Laramie River. The gradients are constant and the surfaces are undeformed, which provides evidence of tectonic stability in the region. The two sets of gradients may reflect different basin areas and sediment sizes. The basins of these streams were not occupied by alpine glaciers; other tributaries of the Laramie River in the Laramie Basin were, however, influenced by glacier meltwaters and sediment supply.
Adapted from pp. 418-423 of Mears, Brainerd, Jr. 1991. "The Laramie Basin." in Chpt. 14 of Quaternary Non-glacial Geology: Conterminous United States. Volume K-2 in The Geology of North America series. Boulder, CO: Geological Society of America.