The Seventh Seal

The Kingdom of Heaven is an arid land, whose weather patterns are dominated by the belt of high pressure air around 30 degrees north.  As a result it has a moisture deficit, which creates low levels of vegetation, wind dominated sediment transportation, and weathering-limited features. However, when it rains, it floods. The arid soils and bare rock have very poor infiltration; as a result flash floods and ephemeral steams transport massive amounts of material and water for limited periods of time. Remember, wind is weak, it can only transport small sediments, and through deflation their removal can create desert pavements.  Wind’s main role in the erosion of arid-landscapes is removal of debris created by salt weathering, but it also can act as sandpaper to create ventifacts.

In the foreground of this picture there is some young desert pavement developing, or more likely an ephemeral stream bed.  In the background the ghost town is built on a differentially weathered outcrop of resistant rock! Unfortunately the town was likely built over, and out of, any talus cones’ debris leaving only part of the pediment visible.

In sediment-rich arid landscapes dunes will form depending on the direction and regularity of the wind. Barchan and parabolic dunes look similar, but the slip faces are on opposite sides. The slip face is where the sand is deposited and falls down when passes the angle of repose; which is about 34 degrees. But it depends on grain size and roughness. Though beautiful, make sure to bring more than enough water when exploring arid landscapes!



To the right of the Sarasin’s helmet there is a barchan sand dune, you can tell that it is not a parabolic dune because the slip face is on the inside of the arch rather than the outside. Some more complex form of sand dune is on the left but you can’t get a good enough look at it to be sure. I personally think it is a barchanoid ridge.