Snow fell on the mountain. It snowed and snowed. The snow did not melt(融化). It became deep and heavy. The snow on the bottom pressed (挤压)together., it became ice. The ice was very wide and thick. It began to move down the mountain. It was like a river of ice. It was a glacier(冰河). Sometimes the glacier moved only a few inches(英寸) each day. As it moved, it took rocks and dirt with it. It changed the land. In some places, it left hills. In some places, when the glacier melted, it made rivers and lakes. A million years ago, there were many big glaciers. Glaciers covered many parts of the world. The glaciers changed the land. Glaciers are still at work today. A glacier in the north of Canada is cutting a new path(路) down the side of a mountain. This glacier will change the land, too.