The loosening and lifting of blocks of rock by glaciers is called plucking.

Here's how it works:

* Freezing Water: As a glacier moves over bedrock, meltwater seeps into cracks and crevices.

* Expansion: When temperatures drop, the water freezes and expands, putting pressure on the rock.

* Plucking: This pressure is strong enough to pry loose pieces of rock, which then become embedded in the glacier's base.

This process is one of the main ways that glaciers erode and shape the landscape.