January 11, 2012
A layer of 230-million-year-old Kaibab Limestone caps the rim.
Stories this photo appears in:
Grand Canyon’s geology offers solace and an education in time
I took a step — a long step — a million years step. Then I stopped, turned and faced north. Perched on the jagged edge of my life, I looked down deep into the shadowed layers of lost worlds — terrible deaths, fractured continents, vanished seas, mass extinctions. Taking a breath, I took another step — a long step — another million years. Curiously, I felt better — my troubles for the moment shrunk to no more than a ledge of Tapeats Sandstone in the wall of the Grand Canyon opposite. A layer of fossilized beach sand laid down 570 million years ago, the Tapeats Sandstone lies atop a mystery of missing stone — dubbed the “Great Unconformity.”