References to his books should carry a warning - something to the effect of:

"may inspire circuitous road trips involving many stops dangerously examining road-cuts on busy interstate highways"

I would pay good money for a field guide/itinerary to accompany "Assembling California".

More directly related to the Green River, I found Wayne Ranney's "Carving Grand Canyon: Evidence, Theories, and Mystery" an accessible/engaging intro to deep geological mysteries.