Geologic change is an all-season process in the Painted Desert. Not far from The Tepees in Petrified Forest National Park, the combined action of wind and water has laid bare a fascinating erosional landscape. Dry the great majority of the time, this area experiences its greatest changes a few times a year—mainly during summer “monsoon” season—when isolated heavy thunderstorm cores wash countless collective tons of sand, clay and silt grains off these slopes and downstream. Periods of strong wind—mainly in the spring and fall transition seasons—also raise dust, redistributing loose particles for inches to many miles, and peppering the rocks with abrasive sand. Then in winter, freeze-thaw cycles pry loose fragments from soft slopes and rocks alike, to be washed or blown away on the other occasions. As a result, and as several others downhill already have done, the dangling hoodoo of sandstone at left surely will bust loose under its own weight and tumble down these slopes sometime soon, if it hasn’t since this visit. Cloud shadows at the top were from a field of deepening convection extending past Winslow that would evolve westward, offering infrequent but spectacular twilight lightning near Sedona.
5 SE Adamana AZ (1 Aug 17) Looking NW
34.9393, -109.7571Works of Wind and Water
Geologic change is an all-season process in the Painted Desert. Not far from The Tepees in Petrified Forest National Park, the combined action of wind and water has laid bare a fascinating erosional landscape. Dry the great majority of the time, this area experiences its greatest changes a few times a year—mainly during summer “monsoon” season—when isolated heavy thunderstorm cores wash countless collective tons of sand, clay and silt grains off these slopes and downstream. Periods of strong wind—mainly in the spring and fall transition seasons—also raise dust, redistributing loose particles for inches to many miles, and peppering the rocks with abrasive sand. Then in winter, freeze-thaw cycles pry loose fragments from soft slopes and rocks alike, to be washed or blown away on the other occasions. As a result, and as several others downhill already have done, the dangling hoodoo of sandstone at left surely will bust loose under its own weight and tumble down these slopes sometime soon, if it hasn’t since this visit. Cloud shadows at the top were from a field of deepening convection extending past Winslow that would evolve westward, offering infrequent but spectacular twilight lightning near Sedona.
5 SE Adamana AZ (1 Aug 17) Looking NW
34.9393, -109.7571