Moraine is the accumulation of debris, boulders, stones, etc. carried and deposited by a glacier.
Drumlins
Stones are small, smooth, and usually used for decoration or construction. Rocks are larger, rougher, and can be made up of multiple minerals.
because it has a smooth out the landscape
drumlin
drumlin
River stones, river rock, or skipping stones
skipping stones!
Striations are typically formed by the abrasion of rocks underneath a moving glacier. As the glacier moves, the rocks embedded in the base of the glacier grind against the bedrock, creating grooves known as striations. These marks can vary in size and direction depending on the movement of the glacier.
Yellow stones
The preprosition in the sentence is "over" and the prepositional phrase is thus "over the smooth grey stones"
Glaciers form smooth hills by eroding and shaping the landscape as they move down a slope. The weight of the ice and the movement of the glacier over time smooth out the terrain beneath it, resulting in the formation of long smooth hills called drumlins.