Grand Canyon National Park: Colorado River Runners 2804
(3000 x 4000) Several rafts from a boating party pass below a sheer cliff of Vishnu schist near the confluence of the Colorado River and Bright Angel Creek at the very bottom of the Grand Canyon. NPS photo by Michael Quinn.
There are three different river trip opportunities through Grand Canyon National Park. Learn more: www.nps.gov/grca/planyourvisit/whitewater-rafting.htm
Grand Canyon's "basement rock" formed 1.8 billion years ago when the North American continent collided with an ancient chain of volcanic islands, much like today’s Hawaiian Islands. Intense heat and pressure from the collision formed the metamorphic rock called Vishnu Schist. From deep under the earth’s surface, molten rock flowed up as magma between the cracks of the Vishnu Schist. As the flowing magma cooled and hardened, it formed igneous rock called Zoroaster Granite. Because of the extreme heat and pressure that folded and changed the metamorphic rock, it is hard to find any fossils in the basement rocks.