Pocono Formation facts for kids

Quick facts for kids Pocono Formation Stratigraphic range: Early Mississippian
Outcrop at Ricketts Glen State Park
Type	sedimentary
Underlies	Mauch Chunk Formation
Overlies	Catskill Formation, Huntley Mountain Formation, Rockwell Formation, and Spechty Kopf Formation
Lithology
Primary	Quartzarenite (sandstone)
Other	Conglomerate
Location
Region	Appalachian Mountains
Extent	Pennsylvania and Virginia
Type section
Named by	Lesley, 1876

The Pocono Formation is a special layer of rock found in the eastern United States. It is mainly located in Pennsylvania, Maryland, and West Virginia. Geologists call a rock layer like this a "formation."

This rock layer formed during the early Mississippian period. This was a very long time ago, about 359 to 323 million years ago! In some places, like Maryland and West Virginia, it is also known as the Pocono Group. Sometimes, the top part of the Pocono Formation in Pennsylvania is called the Burgoon Formation or Burgoon Sandstone.

The Pocono Formation is important because it helps create the tall ridges in the Ridge-and-Valley Appalachians. These are mountains that stretch across the eastern United States. In Maryland and West Virginia, this rock layer is also known as the Purslane Sandstone.

What is the Pocono Formation Made Of?

The Pocono Formation is mostly gray in color. It is made up of a type of rock called sandstone. This sandstone is often "quartzitic," meaning it contains a lot of hard mineral called quartz. The grains of sand in this rock are medium to large in size.

At the very bottom of the Pocono Formation, you will find a rock called conglomerate. Conglomerate is a rock made of many different sized pebbles and stones that are cemented together. Imagine a natural concrete!

Where Can You See the Pocono Formation?

You can see amazing examples of the Pocono Formation in a few places:

• One important spot is in Blair County, Pennsylvania. Here, you can see the Burgoon Sandstone, which is part of the Pocono Formation. It is located in the valley of Burgoon Run, near Kittanning Point.
• Another great place to see this rock is at Sideling Hill in Maryland. There is a huge road cut for I-68 that goes right through the hill. This cut shows off the Purslane Sandstone, which is the same as the Pocono Formation in that area.

How Old is the Pocono Formation?

Scientists use special methods to figure out the age of rock layers. They have determined that the Pocono Formation formed during the early part of the Mississippian period. This period is part of a larger time called the Carboniferous Period.

The Pocono Formation sits on top of older rock layers. These include the Spetchy Kopf Formation and the Huntley Mountain Formation. In some parts of south-central Pennsylvania, the Pocono Formation mixes with another rock layer called the Rockwell Formation. This means they formed at the same time and blend into each other.

Images for kids

• 

  Sideling Hill roadcut