Jefferson City Formation facts for kids

The Jefferson City Formation, also called the Jefferson City Dolomite, is a special rock layer found in the Ozarks region. This area covers parts of Missouri and Arkansas. This formation holds fossils that tell us about life from a very long time ago. These fossils date back to the Ordovician period.

What is a Geologic Formation?

A geologic formation is like a big, distinct layer of rock. Geologists, who are scientists who study rocks, give these layers names. They do this to help understand Earth's history. Each formation has unique features. These features include the types of rocks it contains. They also include the fossils found within it.

What is the Jefferson City Formation Made Of?

The Jefferson City Formation is mostly made of a rock called dolomite. Dolomite is similar to limestone. It forms in ancient seas. Besides dolomite, you can also find other rocks here. These include chert and sandstone.

• Dolomite: This rock is a type of carbonate. It often forms in warm, shallow seas.
• Chert: This is a very hard rock. It is made of tiny quartz crystals. It often forms as nodules or layers within other rocks.
• Sandstone: This rock is made from grains of sand. These grains are cemented together over time.

When Did This Formation Form?

The Jefferson City Formation dates back to the Early Ordovician period. This was a very long time ago. It was about 485 to 470 million years ago. During the Ordovician period, Earth looked very different. Much of the land was covered by shallow seas. These seas were home to many different kinds of sea creatures.

Where Can You Find It?

This rock formation is mainly found in the Ozarks. The Ozarks are a highland region. They stretch across parts of Missouri and Arkansas. In some areas of northern Arkansas, it can be hard to tell the Jefferson City Formation apart from another rock layer called the Cotter Formation.

Why is the Jefferson City Formation Important?

The Jefferson City Formation is important because it contains fossils. These fossils are like clues from the past. They help scientists learn about ancient life. They also help us understand what the environment was like millions of years ago. By studying these fossils, we can piece together Earth's long history.

Who Named This Formation?

The Jefferson City Formation was named by a person named Arthur Winslow. He was a geologist. He named it after Jefferson City, which is the capital of Missouri. This city is located in Cole County, Missouri.

What Rocks Are Above and Below It?

Geologic formations often stack up like layers in a cake.

• The Jefferson City Formation underlies the Roubidoux Formation. This means the Roubidoux Formation is found directly above it.
• The Jefferson City Formation overlies the Cotter Dolomite. This means the Cotter Dolomite is found directly below it.

Scientists study these layers to understand the order of events in Earth's history.