On mohs scale, ice has a hardness of 1.5. why can a glacier cause the grooves and parallel scratches (striations) found in bedrock of granite and gneiss? answer

The glacier carries along with ice, rocks that create the grooves and scratches. As a simple example, paper is relatively soft, yet sandpaper is quite capable of sanding substances with a mohs scale hardness of 9 or lower. Reason is quite simple. The sandpaper has embedded on its surface, silicon carbide which has a hardness of 9 to 9.5. And glaciers can carry boulders and rocks along their bottom surface which in turn can grind and scrape softer materials.

Answer accretion;

Dwould be tehr correct answer