The narrative traces the region's geologic past as an ancient shallow sea and explains how sediment from a great river isolated the basin, leaving a dry sink. It recounts later human irrigation that created a fertile desert oasis, the catastrophic breach of the river that refilled the depression as an inland sea, and the determined efforts led by E. H. Harriman and engineers to close the breach, protect reclaimed lands, and restore agricultural productivity. Chapters combine geology, engineering, flood accounts, and the valley's economic recovery.