Regelation, << `ree` juh LAY shuhn, >> is the process in which ice melts under pressure and refreezes as soon as the pressure is taken away. If two blocks of ice near 32 °F (0 °C) are pressed together for a while, they will be found frozen together when the pressure is taken off. At 32 °F (0 °C), water is denser than ice. Therefore, ice when compressed changes into water. When the pressure is removed, the water expands and refreezes.
A heavy object placed on ice will gradually sink into the ice and bury itself as the ice melts under the object and refreezes above it. A glacier moving along slowly melts and refreezes, slipping a little under pressure each day. In the most recent ice age, which ended about 11,500 years ago, regelated ice in central Canada pushed continental glaciers as far as 2,400 feet (730 meters) up the sides of the Rocky Mountains.
