A Float Trip through the Grand Canyon is
a great Education in Geology
Beginning with rocks that were only 245,000 years old, the Grand Canyon is cut down to rock that is 1.7 billion years old - 1,700,000,000! For the first five days each layer appeared in turn until we got to the Zoaster Granite and Vishnu Schist. For the next 9 days the different layers kept re-emerging and disappearing in earth folds at the river's edge. Lava dams from an ancient volcano create wonderful rapids. The graphic below is from the guidebook that Canyon Expeditions sent us before the trip. It was a great help - I referred to this graphic over and over again to understand what I was seeing ! I highly recommend Canyon Exploration/Expeditions!
This book is available from Canyon Explorations/Expeditions