Glacial Striations: The Tell-Tale Sign of Ice Age Movements

What are the straight scratches on rock surfaces created by glacial abrasion known as?

a. rock flour.
b. varves.
c. glacial striations.
d. moraines.
e. glacial till.

Answer:

The straight scratches on rock surfaces created by glacial abrasion are known as glacial striations.

Glacial striations refer to the parallel grooves or scratches found on bedrock surfaces that have been created by the movement of glaciers. As glaciers advance, they carry rocks and debris in their ice, which act as abrasive tools that scrape against the underlying rock surface. This process is called glacial abrasion. The rocks embedded in the glacier act like a giant sandpaper, grinding against the bedrock as the glacier moves.

The resulting friction leaves behind long, straight scratches or grooves known as glacial striations. These striations provide valuable evidence of past glacial activity and help geologists understand the direction and extent of glacial movement. By studying the orientation and characteristics of glacial striations, scientists can reconstruct the history of glaciation in a particular region and gain insights into the dynamics of ice sheet behavior.

Therefore, glacial striations play a crucial role in deciphering Earth's glacial history and understanding the geological processes associated with glaciation.