GL101 Lecture Notes - Lecture 20: Calm Air, Wave-Cut Platform, Black Sands
Document Summary
If the wind direction shifts or the stone is turned, more than one flat ventifacts - rocks with flat, wind- face may develop on the ventifact. A flat face on a ventifact is produced by the action of wind transported sand grains blasting against the exposed face of a rock or boulder from a particular direction. Hence, three flat faces on a ventifact would indicate a varying wind direction: that is, wind has originated from at least three directions. The process of deflation entails the removal of lighter (fine-grained) particles from a landscape by wind, leaving behind the heavier and coarser-grained fractions. Deflation can lead to a significant reduction of the landscape. A blowout develops on a land surface when the localized removal of sediment (erosion) by wind leads to the formation of a hollow depression. Loess a deposit of wind-blown silt and clay composed of unweathered, angular grains of quartz, feldspar, and other minerals weakly cemented by calcite.
