Here's why:

* Glaciers are powerful forces of erosion and transportation. They carve out valleys, pick up rocks and sediment, and carry them along for miles.

* As glaciers melt, they deposit their load. This includes the rocks and sediment they carried, which are often scattered across the landscape.

* Erratics are often very different from the surrounding bedrock. They might be a different type of rock or have a different composition, indicating they traveled a long distance from their original source.

Erratics are fascinating geological features that provide clues about the history of glaciation in a region.