This is a photo of the Variegated Glacier which lies in the St. Elias Mountain Range of Alaska. You can see a relatively flat snow covered area at the top of the photo. This is an ice field where snow collects and gets compacted. This is also called the accumulation area . When it exits the valley the ice spreads out like pudding and cracks form in the ice called crevasses.
Ice is a material that is both brittle and plastic.
Click here to get a close up look at what a crevasse looks like. This photograph from the American Geographic Society Collection archived at the National Snow and Ice Data Center , University of Colorado. The image on the left shows how snow gets compacted to form ice. There are many people interested in drilling ice cores in Antarctica and Greenland. They can analyze a number of properties of the ice cores to determine past climate history.