As a glacier moves into a warmer area, the ice begins to melt around the edges of the moving glacier. After this happens the glacier starts to wear or shrink away. Rocks and sediments that were frozen in the ice are left behind. The materials that are deposited is called till. Big rocks, boulders by retreating glaciers are called erratic.
Central park is known for having carried many boulders.
The boulders are like bedrock located hundreds of kilometers away. The boulders are too heavy and too big to have been moved by running water or by humans. The only thing that could've moved these great big and heavy boulders is a glacier. It so happens that 65 million years ago The Wisconsin Glacier passed through Central Park. And most of the shaped rocks that this glacier formed has been more of the fascinating aspects of rock study in Central Park today.