Lesson 4 Changing Earth’s Surface – Max learned how ice changes Earth’s surface. He explored how glaciers cause erosion as they move centimeters each day. He learned that Alpine glaciers form in mountains flowing downhill and continental glaciers or ice sheets cover large areas of land moving outward from central locations. Next he learned about glacial debris such as till which is a mixture of various sizes of sediment deposited by a glacier and a moraine which is a mound or ridge of unsorted sediment. The glacier acts like sandpaper over rocks. Then Max learned about the features of a glacier: horn, arete, cirque, U-shaped Valley, hanging Valley.