This is a glacier that I photographed from a small plane on the south eastern slope of Mt. Denali in Alaska. With only the perspective of the mountain ridges, it is hard to visualize the size of the glaciers in the area. This particular glacier is over 30 miles long and starts about 18,000 feet up the side of Denali. As the glaciers flow, they drag rock material along their edges (called lateral moraines). When smaller glaciers join together, the edge rock material forms stripes down the middle of the newly formed larger glacier (called medial moraines) . Some of the cracks in the surface of the glacial ice are filled with crystal clear blue water and freshly frozen ice.