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Arcadia Park Shale facts for kids

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Arcadia Park Shale
Stratigraphic range: Mid to Late Turonian
92.5–90Ma
Type Formation
Unit of Eagle Ford Group
Sub-units Kamp Ranch Limestone, Bells Sandstone, Maribel Shale, Sub-Clarksville Sandstone
Underlies Austin Chalk
Overlies Britton Formation
Lithology
Primary Shale
Other Marl, limestone, sandstone, volcanic ash beds
Location
Region Texas
Country United States
Type section
Named for Arcadia Park railway station, Texas
Named by W. L. Moreman

The Arcadia Park Shale is a special type of rock layer found in the ground. Geologists, who study rocks and the Earth, call it a geologic formation. It is part of a larger group of rocks known as the Eagle Ford Group. You can find this rock layer appearing at the surface, which is called an outcrop, in northern East Texas.

This rock formation was created a very long time ago, during the Middle to Late Turonian age. This was a period within the Late Cretaceous time, when dinosaurs roamed the Earth!

What is the Arcadia Park Shale?

The Arcadia Park Shale is mainly made of a rock called shale. Shale is a fine-grained sedimentary rock that forms from mud and clay. It often splits into thin layers.

Where is it Found?

The Arcadia Park Shale was first described by a scientist named W. L. Moreman. He studied the rocks near an old railway station called Arcadia Park, which is west of downtown Dallas. In that area, the rock layer is about 100 feet (30 meters) thick.

Right below the Arcadia Park Shale, there's another rock layer called the Britton Formation. There's a gap in the rock record between them, which scientists call an unconformity. This means some time passed, or some rock layers were eroded away, before the Arcadia Park Shale started forming.

What is it Made Of?

The very bottom part of the Arcadia Park Shale is a thin layer of limestone. This special limestone is called the Kamp Ranch Limestone. It's made up of broken pieces of Inoceramus clams. You can also find shark's teeth in this limestone!

Most of the Arcadia Park Shale in the Dallas area is made of shale. This shale often contains round, hard lumps called concretions. North of Dallas, you can also find layers of sandstone within the Arcadia Park Shale. These sandstone layers have special names like the Bells Sandstone Member and the Sub-Clarksville Sandstone. The shale found above the Bells Sandstone is called the Maribel Shale.

Fossils Found Here

The Arcadia Park Shale is a great place to find fossils! Scientists have discovered many ancient creatures preserved in these rocks, including:

  • Shark's teeth
  • Other fish remains
  • Ammonites (ancient sea creatures with spiral shells, like a nautilus)
  • Inoceramus clams (a type of large clam)
  • Oysters
  • Foraminifera (tiny, single-celled organisms with shells)

Oil Production

The Sub-Clarksville Sandstone, which is part of the Arcadia Park Shale, is an important source of oil in East Texas. This means that oil can be found and collected from this rock layer.

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