Stone Mountain (Pennsylvania) facts for kids

Stone Mountain is a long, narrow hill or ridge in central Pennsylvania, United States. It's part of the famous Appalachian Mountains. This ridge helps separate the Kishacoquillas Valley from an area known as the Seven Mountains.

Stone Mountain sits right on the border between Mifflin and Huntingdon counties. It's a natural landmark that helps define the landscape of this part of Pennsylvania.

Exploring Stone Mountain

You can find several roads that cross or run near Stone Mountain. Pennsylvania Route 305 goes over the ridge. It also follows a valley that was formed by a crack in the Earth's crust, called a fault line. This area is close to Greenwood Furnace State Park.

Another road, Allensville Road, crosses the top of the ridge north of Allensville. Barrville Road also passes through a special dip in the ridge called a wind gap. A wind gap is a low point in a ridge where a river used to flow, but now it's dry.

Interestingly, no rivers cut through Stone Mountain. This means there are no water gaps here. A water gap is a place where a river has carved a path directly through a mountain ridge. Saddler Creek flows near the southern base of the ridge, close to the town of Mill Creek.

How Stone Mountain Formed

Stone Mountain is a great example of how different types of rock create mountains. The mountain's shape is due to its geology, which is the study of Earth's rocks and how they change.

The top and steeper side of Stone Mountain are made of a very strong rock layer called the Silurian Tuscarora Formation. This rock is tough and resists being worn away by wind and water. Below this, on the southeast side, is an older rock layer called the Ordovician Juniata Formation.

Even lower down, on the slopes facing the Kishacoquillas Valley, you can find the Bald Eagle Formation. This rock layer forms a steep step on the mountain. Below that, the top part of the Reedsville Formation contains interesting clues about the past. In this rock, scientists have found fossils of ancient sea creatures like brachiopods. Fossils are the preserved remains or traces of living things from long ago.

On the other side of the Kishacoquillas Valley, you'll find Jacks Mountain. It has the same rock layers as Stone Mountain, but they are in the opposite order. This is because of a large fold in the rock layers called an anticline.