During the retreat of a glacier, pebbles and bare rock that were under the sheet are exposed to the air. What is likely the next event to occur? ( don’t mind the blue dot )

I think it’s cause About 200 years ago, the glaciers started melting, which scientists call "glacial retreat." With the retreat of the glaciers, ridges of rock and debris called moraines remained. Moraine is little more than bare rock and no plant life can exist on it until the first stages of succession begin.