The Grand and the Green Rivers form the Colorado River here.  John Wesley Powell expedition passed here on July 16, 1869.

Jack Crane

Lewis and Clark Expedition

The Lewis and Clark Expedition, also known as the Corps of Discovery Expedition (1804–1806), was the first transcontinental expedition to the Pacific coast undertaken by the United States. Commissioned by President Thomas Jefferson, it was led by Meriwether Lewis and William Clark.

• http://en.wikipedia.org/wiki/Lewis and Clark Expedition
• Page 165 - Dolnick, E., 2001, Down the Great Unknown: John Wesley Powell’s 1869 Journey of Discovery and Tragedy Through the Grand Canyon: HarperCollins Publishers, New York, 367p.