Jun 6 2014
Glacial striations are lines or scratches that occur on a smooth rock surface, caused by glacial abrasion. They mostly occur on bedrocks embedded in the bottom of a massive glacier. Glacial striations are usually straight, multiple, and parallel.
Although glaciers are found only in the polar regions today, the scratched lines are evidence that glaciers were found in several other parts of the world in the geologic past. The lines also act as an indicator of the direction the glacier moved, and the depth and extent of weathering of gouges helps to estimate the duration of the post-glacier exposure of the rock.
For example, about 30,000 to 10,000 years ago glaciers were present in the high mountains of Utah. When these glaciers moved, the sediments in them scratched the rocks beneath, leaving behind polished surfaces and striations that can be seen even today.
Glacier movement can be compared to that of a bulldozer, as it strips away layers of rock and moves them off to the side. It is also compared to a large piece of sandpaper as it erodes, scrapes, and grinds down the rocks.
SOurces and Further Reading