Existing comment:
The Vanishing Sea: 250 to 66 million years ago:
The red sands that you see in front of you were laid down about 200 million years ago during the Mesozoic Era. Then the sea retreated for the last time, and this region became a gigantic plain of sand, silt, clay and gravel. Sluggish streams meandered across the land.
Wind and rain, heat and cold operated on the exposed ancient sediments, wearing them away and forming beds of mud, silt, sand, and gravel. For tens of millions of years, a desert even more severe than today's covered this region. Strong winds blew thousands of feet of sand from distant highlands, creating huge dunes. These ancient sand dunes, now "fossilized" and eroded into exotic shapes, are the spectacular red and white formations of the Valley of Fire.
The original sequence of all these deposits is shown in the geologic column on this panel. But -- and most important to understanding the view across the valley -- this sequence was changed about 100 million years ago, when older materials were shoved up on top of younger ones, creating the Muddy Mountains. At the same time the thick sandstone deposits in front of the Visitor Center warped upward and eroded, exposing the soft shales of the ancient sea bed underneath. These quickly wore away, creating the broad valley if front of you along which the park road now runs.
Geological Terms:
* Paleozoic Era: 550 million years to about 250 million years ago.
* Mesozoic Era: 250 million years to about 66 million years ago.
* Cenozoic Era: 66 million years ago to today.
Although the remnants of the Paleozoic thrust plate are visible in the hills, only Mesozoic rocks are present in the valley.
The upper plate of the Muddy Mountain Thrust has been eroded away in the Valley of Fire area.
Approximately 10,000 feet (3 km) of deposits have been lost to erosion over the past 70 million years. |