If you wander around Central Park in New York City, you will eventually encounter random, large boulders that are made of a type of rock not found in the area. How did these large boulders get to Central Park?
A. The Parks and Recreation Department placed them there for kids to play on.
B. They were carried by rivers and deposited in point bars.
C. They were carried by glaciers and dropped to form glacial erratics.
D. They were placed there by a giant tsunami millions of years ago.

There four different types of bedrocks in the Manhattan as in the Central park the Manhattan schist and the Hart-land shirts which are metamorphosed sedimentary rocks, and exposed in the outcrop. And some consists of the igneous rocks that are formed by billions of years ago. At the time of the Grenville progeny and it occurred in the creation of the ancient super landmass.

Various glaciers have covered the area of the central park in the past and most recently was the Wisconsin glacier about 12,000 years ago that formed erratic.