Round 100: Tossup 20

The Lettau equation modeling the movement of this substance agrees with Pierre-Yves Belly’s experiments verifying the Kawamura curve. The RDP/DP ratio was introduced to model the movement of this solid substance, which corresponds to anything between -1 and 4 on the Krumbein phi scale. The movement of this substance is proportional to (15[1])the square root of d over 250 micrometers times u-star cubed according to the (*) Bagnold (“BAG-nohld”) formula. This substance can be horizontally secured with a groin. This material moves by saltation (-5[1])from the stoss (-5[1])to the lee side of certain features which come in (10[1])“barchan” and “parabolic” types. The vast majority of the Earth’s mobile form of this material is found in ergs. For 10 points, name this material that makes up dunes. (10[1])■END■ (10[2])

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