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Valley Glaciation
The Aletsch glacier in Switzerland is approximately 14 miles in length; several of the Himalayan glaciers are 25 miles in length and the Seward Glacier in Alaska is nearly 50 miles in length. Despite the impressive size of some of the valley glaciers of the present, they are much smaller than they were during the Ice Ages.
Much like streams, the central portion of a glacier flows faster than the sides; similarly, the top flows much faster than the bottom. The amount and rate of movement of the surface regions can easily be determined by placing a row of markers across the glacier.
Ice subjected to sufficient pressure becomes fluid, the fluid moves to a pore space and, as the pressure there is less the water refreezes... this can easily be demonstrated. One can support a block of ice and attach a weight to the ends of the wire below. The wire in contact with the ice and under the influence of the pressure will cause the ice to melt. The liquid water will move the upper side of the wire and refreeze. By this means the wire will pass through the ice without any trace of its passage. In a similar manner, the ice of a glacier can pass over a rock obstruction, then the rock may be plucked from its bed and incorporated with the load of the glacier.