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"Dragons diving into the sea" - differential erosion

Dragons diving into the sea - differential erosion-

"Dragons diving into the sea" - differential erosion - This geological feature named "Dragons diving into the sea" is the result of differential erosion on a kind of sedimentary rock called shale.

Shale is a sedimentary rock composed of clay particles. Can you point out the major difference between conglomerate and shale? During sedimentation, the clay particles settle intermittently. Every time a new flood of clay settles, apparent sedimentary boundaries are formed. Eventually, a fine textured sedimentary rock is formed with well-stratified layers.

Later, earth movement tilted and exposed the shales which are composed of alternating resistant and nonresistant layers. The nonresistant units were eroded while the resistant layers were left standing as long asymmetric ridges, which look like rows of dorsal horns of dragons.

This is a good place for practicing the measurement of dip and strike. Dip is the angle between the horizontal plane and a structural surface while strike is the bearing of a horizontal line on a bedding plane. You can select several resistant layers and measure the dip angles and strike orientations. What can you tell from the dip angles and strike orientation?

 

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Last revision date:1 September 2004