Complex sentence: In the eons before human occupation of the Americas, the Shoshone River issued from the Absorakee Mountains and flowed across the Bighorn Basin in a valley floor that lay along the Polecat Bench, north of Powell.
Split into simpler sentences: In the eons before human occupation of the Americas, the Shoshone River issued from the Absorakee Mountains and flowed across the Bighorn Basin. The Shoshone River flowed in a valley floor that crossed the Polecat Bench, north of Powell.