The Quaternary Period represents the time in Earth’s history in which we live, and encompasses about the last 1.65 million years of geologic time. Along with the older Tertiary Period, they make up what is called the Cenozoic Era, also called the ‘Age of Mammals.’ The Quaternary itself is divided into two epochs, the older Pleistocene Epoch (also known as the ‘Great Ice Age’), and the younger Holocene Epoch, which we are living in today. Most geologic time scale charts place the start of the Holocene around 10,000 years ago, about when the last great episode of continental glaciation ended.
At about this time, and a little earlier, melt-waters would flow eastward off of the Rocky Mountains from the melting of Pleistocene glaciers. These melt-waters formed great river systems (such as the Arkansas, Cimarron, and Canadian River systems) that continually sculpted the Oklahoma landscape into what we see today. As such, the Quaternary represents a time of erosion in Oklahoma. Surface rocks are continually being exposed to the elements, and weathered to form loose, unconsolidated material. This loose material may remain stationary to form soil, or streams, rivers, and even the wind can carry the loose material away. The transported sediment will eventually make its’ way to the Gulf of Mexico, but until then it may temporarily reside on the banks of rivers, or in lakes. These temporary deposits of gravel, sand, and clay form unconsolidated terrace deposits that may reach as much as 100 feet in thickness, and occur adjacent to modern rivers. Pleistocene-age terraces may occur hundreds of feet above modern flood plains, while Holocene terraces and flood plains occur adjacent to river channels. Fossils may also be found in these Quaternary sedimentary deposits, and may consist of wood, clams, snails, and teeth and bones of horses, camels, bison, and mammoths (Johnson, 1996).
Some of these older terrace deposits can be modified by strong winds, which blow the loose sand and silt into dune structures and ridges. Little Sahara State Park is just such a deposit where loose sand from older alluvial deposits of the Cimarron River was blown and piled into dunes 10’s to 100’s of feet thick. Many of the major drainages in the west part of the State (Cimarron, Canadian, and North Canadian) have extensive Quaternary sand dune deposits on their north side, which suggest that the prevailing winds come out of the southwest.
Reference: Johnson, K. S. 1996. Geology of Oklahoma, p. 1-9. In, K. S. Johnson and N. H. Suneson (eds.), Rockhounding and Earth-Science Activities in Oklahoma. Oklahoma Geological Survey Special Publication 96-5.