Definition of "scaur"

The crag is high, the scaur is deep, / Yet shrink not from the desperate leap […] .

1810, The Lady of the Lake, Walter Scott, 3.XIII

There are "stags of ten" roaming abroad unstalked; and perchance that is a hart royal swelling his broad front on yonder scaur.

1859, Walter Cooper Dendy, The wild Hebrides, page 67