Aerial view of the Grabens, Canyonlands National ParkThe features grabens are caused by blocks of rock sinking between parallel faults in the Earth. Most of the grabens are 25 to 75 meters (82 to 246 feet) deep and extend for about 25 kilometers (16 miles).The origin of these distinctive features dates back some 300 million years, when a shallow inland sea covered the area. Salty deposits called evaporites accumulated along the bottom of the ocean basin. As more material was deposited, the evaporite layer grew to be more than a thousand meters thick in some places.Environmental conditions gradually changed over time. During some periods, ocean levels were higher and deposited layers of limestone. When sea levels were lower and the crust was exposed to air, layers of sandstone, mudstone, and siltstone were laid down on top of the evaporites. The result was a layer-cake of rock formations that alternate between shades of red, white, gray, and brown.The soft salt layer underneath them acted like a lubricated surface for this sliding. While the salt layer underneath was able glide plastically, ordinary rock types like the sandstone above it could not. The land was stretched as it slid towards the gorge, and the brittle sandstones and limestones fractured and faulted.
The Operational Land Imager (OLI) on Landsat 8 captured this image of Canyonlands’ grabens on May 13, 2014.
NASA Earth Observatory images by Jesse Allen and Robert Simmon, using Landsat data from the U.S. Geological Survey. Googlobetales
A small glimpse of the Shangri-La of bouldering in a hidden corner of Guysborough Co, Nova Scotia. Benoit Lalonde’s post
Benoit is a local backcountry obsessive who’s apparent goal is to see every waterfall, cliff, cave or other feature there is. So far he has seen 1000’s.
I have walked over terrain like that and it is no fun. Holes and rocks that roll under foot make it leg breaker terrain and Benoit has my respect. He does this stuff every weekend without injury.