How do glaciers create striations?
Glacial grooves and striations are gouged or scratched into bedrock as the glacier moves downstream. Boulders and coarse gravel get trapped under the glacial ice, and abrade the land as the glacier pushes and pulls them along.
What do glacial striations tell about a glacier?
Glacial striations or striae are scratches or gouges cut into bedrock by glacial abrasion. As well as indicating the direction of flow of the glacial ice, the depth and extent of weathering of the striations may be used to estimate the duration of post-glacier exposure of the rock.
What are glacial striations and how are they formed?
Glacial striations are a series of long, straight, parallel lines or grooves scratched onto a bedrock surface by rock fragments lodged in the base of a moving glacier. They typically form on hard rock, such as quartzite, that is relatively resistant to erosion.
What causes rock striations?
In geology, a striation is a groove, created by a geological process, on the surface of a rock or a mineral. Striations can also be caused by underwater landslides. Striations can also be a growth pattern or mineral habit that looks like a set of hairline grooves, seen on crystal faces of certain minerals.
Where do striations form?
Over time, the glacier moves over rock and sediment, leaving striations or striae, on the rock surfaces that can reveal the direction that the glacier was flowing.
What do the tracks a glacier leaves on rocks indicate?
As the glacier sands the rock, it leaves behind long scratches that form in the direction of the glacial movement called glacial striations. Seeing these scratch marks is a sure sign that a glacier once covered the land.
What does glacier erosion look like?
Glaciers erode the underlying rock by abrasion and plucking. Glacial meltwater seeps into cracks of the underlying rock, the water freezes and pushes pieces of rock outward. The rock is then plucked out and carried away by the flowing ice of the moving glacier (Figure below).
What causes striations and glacial polish on bedrock quizlet?
What causes striations and glacial polish on bedrock? Grains of rock embedded in the ice grind against the bedrock. The ice slides over bedrock on a thin film of meltwater.
What causes striations and glacial polish on bedrock *?
Striations and Glacial Polish. Striations and Glacial Polish: As glaciers pour off the mountain highlands, they carry vast quantities of weathered and eroded rock. When the rock laden ice scrapes against the mountain valleys, scratch marks or “striations” develop parallel to the glacier’s path.
What is terminal moraine in geography?
A terminal, or end, moraine consists of a ridgelike accumulation of glacial debris pushed forward by the leading glacial snout and dumped at the outermost edge of any given ice advance. It curves convexly down the valley and may extend up the sides as lateral moraines.
What happens if we melt glaciers?
What are the effects of melting glaciers on sea level rise? Melting glaciers add to rising sea levels, which in turn increases coastal erosion and elevates storm surge as warming air and ocean temperatures create more frequent and intense coastal storms like hurricanes and typhoons.