SINE

I know some people do not like that the river is blocked by Hoover Dam and Glen Canyon Dam to make power or prevent flooding. Some say this is a problem for animals and fish. It's a problem even for people who remember how it was. But this has happened many times before any people ever saw it. I quote from books:

Edwin D. McKee, Ancient Landscapes of the Grand Canyon Region, 1931 as in Bruce Babbitt, ed. Grand Canyon: An Anthology (Flagstaff: Northland Press, 1978):

Among the rocks below Desert View (Navajo) Point and bordering on the Colorado River [there] may readily be seen several black cliffs formed by the volcanic activity of [the Algonkian Era]...

NPS Retrieved and edited 12/2/2008:

In the western Grand Canyon hundreds of volcanic eruptions occurred over the past two million years. At least a dozen times, lava cascaded down the walls of the Inner Gorge, forming massive lava dams that blocked the flow of the Colorado River. Three of these lava dams were over 1,000 feet high, forming lakes similar to reservoirs such as Lake Powell or Lake Mead. Some of the lakes were over 100 miles long and filled the lower portion of the Grand Canyon for many years before finally over-topping the dam and eroding much of it away. Cinder cones and the remnants of lava flows and dams are visible in the Toroweap area and from the river near Lava Falls.

● Get book