Here's why:
* Glacial Deposits: Grand Island sits within the Great Plains region, which was heavily impacted by the Pleistocene glaciations. The bedrock is primarily composed of glacial till, a mixture of clay, sand, gravel, and boulders deposited by retreating glaciers.
* Loess Deposits: The region also has significant deposits of loess, a fine-grained silt that was blown in by wind after the glaciers retreated. This loess contributes to the fertile soils of the area.
While the bedrock itself was formed during the Pleistocene, the landform of Grand Island itself is more recent, shaped by erosion and deposition since the last glacial retreat.
