Figure 17.17
Glacial abrasion and glacial flour. (A) This outcrop of Manhattan schist in Central Park, New York, has been smoothed by glacial erosion. Glacial striations are visible as parallel grooves in the rock. The faint shine of the rock comes from glacial polish. (B) Moraine Lake, Banff National Park, Canada, is famous for its brilliant blue water. The uniformly small particles of suspended glacial flour in the water reflect mostly blue wavelengths of light.(A. © Patti McConville/Alamy; B. © Philip and Karen Smith/The Image Bank/Getty Images)