A LAND OF GREAT DUNES
Red Rock 180 million years agoIf you could travel back in time, about 180 million years, you would find yourself standing in a vast field of towering red sand dunes that stretched across much of the Southwest. This immense dune field was one of the largest that has ever existed on earth. The region was very arid and looked similar to the dune fields of the modern-day Sahara Desert in Africa.
Over time, underground water moving through the dunes carried away much of the red colr and left behine calcium carbonate. This process cemented the sand into rock.
This rock forms the color sandstone cliffs and hills of Red Rock Canyon National Conservation Area.
ANCIENT DUNESLook across to the giant sandstone hills before you and notice the sweeping curves in the stone. These layers, known as cross beds, were developed while the sand dunes were still active.
As the wind blew, the dunes migrated, and their sand formed inclined layers. The tops of old dunes were reformed and new ones were built, leaving a record of cross-cutting curves in distinct multiple layers.
CREATION OF CROSS BEDSSand grains are transported by winds up the windward slope of a dune, and they slide down the steeper leeward side, depositing sand in distinct layers or beds. This transportation and deposition results in a slow forward migration (movement) of the sand dunes.
FROM CROSS-BEDDED DUNES TO STACKS OF STONE
- In a vast field of sand dunes, the migration of a dune partially erodes the dune in front of it. As this occurs, sand is deposited in curving layers and the dune "climbs the back" of the dune in front of it.
- This new series of curving layers is oriented at angles to those in the remnants of the dune below it and are known as cross beds. The continued forward climbing movement of dune after dune resulted in the stacking of layer upon layer of cross-bedded sands.
- Underground water moving through these deep piles of sand left behind calcium carbonate that cemented the sand grains together and turned the sand to stone.
Information courtesy of
U.S. Department of the Interior Bureau of Land Management
Red Rock Canyon National Conservation Area
Saturday, November 22, 2008
Information from a sign
I think you might be interested in some information we read on a sign in the park. It's about the formation of this beautiful area. Denise & I are always fascinated by this type of information, so I thought I'd take a few minutes to copy the words on one of the signs as the first stopping point within the park.
