Current Earth Science

Humans, the Short End of the Time Scale

The long-winded history of the Great Plains is recorded in the geological features we see today. The Precambrian shows itself in outcrops of the pink Town Mountain granite, the Packsaddle schist and Valley Springs gneiss. These rocks tell a story of massive chambers of boiling-hot magma being pushed to the surface to cool, and surrounding rocks being metamorphosed by intense heat and pressure. In the Paleozoic and later in the Cretaceous, ancient shallow seas covered the inner continent and produced carbon-rich rocks. Limestones, shales, and fossilized reefs are scattered throughout the Great Plains and nearby areas, evidence that the area was not always the ‘Great American Desert’. Decaying plant matter built up and compressed over time resulted in coveted coal deposits. When the waters retreated, the temperatures started going down, too.

Now, the Great Plains are dusted by a layer of younger sediments—sand and gravel and soil—eroded from the Rocky Mountains on the western border. These sediments help trap water underground in aquifers, supplying the region and its inhabitants. It is no surprise that pockets of water have been attracting all sorts of living beings for thousands of years, and early humans were no exception.

The common consensus among archaeologists is that humans began living on the Great Plains at least 11,000-11,500 years ago, based on carbon dating of various artifacts like bones, stone flakes and tools. This time overlaps with the last Ice Age, and the time of giant creatures like mammoths and saber-tooth cats (see Miocene and Mammoths). In 2005, a study took advantage of some broken mammoth bones that had been on display at the Denver Museum of Nature and Science for nearly 30 years. The bones appeared to have been broken by humans rather than by natural means, and were carbon dated at about 12,200 years old. Many scientists are drawn to the significance of discovering the oldest site with clear evidence of human habitation, and so research continues.

Humans have been fascinated by the challenges and opportunities offered by life on the Great Plains for a very long time, whether because of water and food resources, the hunt for gold and precious materials, agriculture, or an adventure. This curiosity is prominently realized in the mid-1800s, when Americans were surveying the Territories and some people thought that rain would follow the plow.

 

Featured photo courtesy of U.S. National Archive:

Hikers Terry Mcgaw and Glen Denny Enjoy a View of the Maze from the Top of a Ridge Separating Two Canyons. The Maze, a Wild and Rugged Region in the Heart of the Canyonlands, Has No Footpaths, and Hikers Enter by Means of Ropes Or Steps Cut in the Rocks,

 

See the following sources for more info:

http://geology.teacherfriendlyguide.org/index.php/rocks-sc/rocks-region4-sc

https://www.geosociety.org/documents/gsa/timescale/timescl.pdf

Denver Post Staff Writer. “Museum’s Mammoth Bones Exhibit New Life After Nearly 30 Years on Display, Fossils Found in Kansas Are Causing Scientists to Re-examine When Humans Arrived on the Great Plains. (DENVER AND WEST).” The Denver Post (Denver, CO), 2005.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s