This is 13 million year old Lava Butte, seen from where
Lake Mead Boulevard joins the Northshore Road. At a
mere 2,871' above sea level, Lava Butte was formed when
fresh lava forced itself between the older, adjacent
layers when they were horizontal. As with many rocks in
the Lake Mead region, tectonic activity has moved this
rock tens of miles to the west from where it first
spewed from the Earth.
The many geologic layers that help make the Grand Canyon
so spectacular are exposed in Rainbow Gardens, which
surround Lava Butte between Las Vegas and Lake Mead.
Although the display isn't as memorable as at Grand
Canyon, the numerous and colourful north-south ridges
offer insight into our Earth's "shady" past.
Exposed rocks in this region date back more than one
billion years, representing every major era of Earth's
development. The oldest exposed rocks are to the west
in and around Frenchman Mountain, including the 1.8
billion year old Vishnu Schist, the oldest exposed
rock in North America.
Yes, that's a much younger Lake Las Vegas in the
foreground. It's basically a retreat for rich people.
March 21, 2008