Activity 2: Do at School!

What Doesn't Belong?


Most of the rocks we find in Central New York are grayish rocks made of sediment (sand, lime, and mud) laid down at the bottom of a shallow sea a long time ago. Occasionally we find colorful rocks with crystals (sometimes even bands of crystals) lying loose on the ground. These colorful crystal rocks are very common in the Adirondack mountains in northeastern New York and in southern Canada. During the Ice Age glaciers scraped southward from Canada, and, like bulldozers, they pushed pebbles and boulders along in front of them. During warmer periods when the ice melted away, these colorful crystal pebbles were left behind. These foreign pebbles are called "erratics" because they are unlike most of the rocks found in the area. [Different kinds of rocks you might find]

Take a walk with your family or classmates and collect several small rocks from around your neighborhood. Try to sort them into three categories:

  1. Gray and white rocks - these are rocks made of sediment. Some might even contain fossils!
  2. Colorful crystal rocks - these are rocks that formed under the surface of the earth and may have been carried to your neighborhood by a glacier 12,000 years ago.
  3. Mystery rocks - these may be pieces of concrete or rocks carried into your neighborhood by people.

Which kind of rock did you have the most of? Did you find any rocks that might have been left by the glaciers? Did you find any rocks with fossils in them?

Main Message: Classifying rocks can answer questions about the history of an area.

Connections: Activity 7, Ice Age Mud from an Ancient Pond, will allow students to classify rocks and fossils from the sediment surrounding a Mastodon.


The Paleontological Research Institution
1259 Trumansburg Road
Ithaca, NY 14850 phone: 607-273-6623 fax: 607-273-6620
Questions about the Website? Tell us!