For the second assumption at work in the minds of the explorers of the day was that the geography west of the Continental Divide was the same as the geography east of it. All had assumed that in the same way the land rose gently over thousands of miles to a peak, it would also descend gently to the Pacific Ocean. In the same way they had been able to take a keelboat and canoes up a river, they’d be able to drift downriver to the ocean.
