Death Valley and the Basin and Range Province are largely the result of extensional forces dating from the last 15-20 million years. The crust was stretched and broken up into horsts and grabens, and earthquakes today still mostly reflect the heritage of the intense stretching of the earth's crust. It wasn't always that way. For something like 200 million years, the region was under the influence of compressional forces, courtesy of the massive subduction zone that once existed off the California coast (it still exists to the north as the Cascadia Subduction Zone). As the ocean crust sank beneath the edge of the North American continent, the rocks that had originally formed the passive continental margin were pushed skyward and intensely folded. In places the folds literally turned the rocks upside down.
Because the Death Valley graben has been sinking through time, the valley is deeper and more narrow towards the edge of the range, since the river gradient is steeper and erosion faster. The narrows of Titus Canyon are memorable, being barely wide enough to accommodate the vans. Most of the students got out and walked the last mile (in the dark), because the canyon is so scenic in the lower reaches.