This richly illustrated book is both a visitor's guide to one of southwestern Ontario's most striking landforms-Elora Gorge on the Upper Grand River-and a thorough, accessible introduction to its natural and recent human history. The book introduces rivers that flow in bedrock, between rock walls, and through precipitous gorges. It then leads the visitor to viewpoints on and excursions through the gorge, with a wealth of Information about its rocks, fossils, caves, cliffs, rockslides, rockfalls, floods, and erosional processes. Hewitt takes the reader through five "ages" of the gorge, from the First Age, when the gorge bedrock originated as reef limestone 430 million years ago in prehistoric tropical seas, all the way to the Fifth Age, when the gorge entered the Anthropocene as European settlers came to disrupt and dominate its development and unlock its secrets. Full of original photographs, maps, and diagrams, Rivers in Rock is an authoritative guide to Elora Gorge that will fascinate visitors and researchers alike.