* Formation: The geological processes that created the Great Plains began millions of years ago. The Rocky Mountains, for example, began rising around 80 million years ago, and their uplift contributed to the formation of the plains.
* Erosion and Deposition: The Great Plains are constantly being shaped by erosion (wind and water wearing away the land) and deposition (sediments being deposited by rivers and glaciers). So, the landscape is constantly changing.
* Modern Definition: The Great Plains, as a geographical region, are more about their climate and vegetation than a specific geological age.
In short, there isn't one definitive age for the Great Plains. They are a dynamic landscape with a long and complex history.
