Pluck and Carry

Pluck and Carry. . If we think of volcanoes as mountain builders, then glaciers are mountain remodelers. This lone rock pays tribute to the rearranging forces of glaciers. Glaciers carve, grind, and excavate mountains in ways that geologists easily recognize. This huge rock is called glacial erratic , a boulder out of context., Notice the smooth surface of the rock at your feet. This rock was worn by the friction of a glacier that moved over it about 18,000 years ago. The lone boulder, which is of a younger rock type than the surface rock, was carried and dropped here by the same glacier. As the glacier formed and flowed from Bumpass Mountain behind you, it plucked the boulder from the mountain’s side and engulfed the rock into the ice mass. Gravity moved the ice mass downslope over the surface rock. By the time the boulder reached this location, the glacier melted and set the rock at rest here., The scratched and polished appearance of the surface rocks at the edge of the parking lot attest to the action of glaciers. The direction of the scratches indicate the path the ice mass followed.