Glacial striations are scratches or grooves found on rocks that have been shaped by the movement of glaciers. As glaciers advance, they carry along debris and sediment, which can scrape against the underlying rock surface. This process creates distinct patterns that can reveal the direction of the glacier's movement. These markings are important for understanding past glacial activity and the history of Earth's climate. By studying glacial striations, scientists can learn about the size and flow of glaciers, as well as the environmental conditions during different geological periods.