| Red Canyon in the lower foreground consists of Precambrian-age Hakatai Shale (about 1.2 billion years old). On the opposite side of the Colorado River (at the center-right of the image) are massive basalt cliffs of the Cardenas Lavas (also of Precambrian age, about 1.1 billion years old). The Cardenas Lavas dip gently to the east beneath the Great Unconformity. The horizontal layers of the Tapeats Sandstone lie above the Great Unconformity. The Tapeats Sandstone formed from shallow marine and intertidal zone sediments that were deposited in the Cambrian Period (about 540 million years ago). In contrast, the Kaibab Limestone on the rim of the Grand Canyon is about 250 million years old. Click here to see the stratigraphic section for Grand Canyon National Park; see also Billingsley (2000), and Timmons and others (2009). |
