Lake Waco Formation facts for kids
Quick facts for kids Lake Waco FormationStratigraphic range: Mid Cenomanian-Early Turonian ~96–93.5Ma |
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|---|---|
| Type | Geological formation |
| Unit of | Eagle Ford Group |
| Sub-units | Bluebonnet Member, Cloice Member, Bouldin Member |
| Underlies | South Bosque Formation |
| Overlies | Pepper Shale |
| Lithology | |
| Primary | Shale |
| Other | Marl, limestone, volcanic ash beds |
| Location | |
| Region | East Texas |
| Country |  United States |
| Type section | |
| Named for | Lake Waco near Waco, Texas |
| Named by | Adkins and Lozo |
The Lake Waco Formation is a special layer of rock found in central Texas. It is part of a larger group of rocks called the Eagle Ford Group. This rock layer formed a long, long time ago, during the Late Cretaceous period. This was about 96 to 93.5 million years ago, when dinosaurs still roamed the Earth!
Scientists W. S. Adkins and F. E. Lozo named the Lake Waco Formation in 1951. They named it after the rock layers they found near Lake Waco, which is close to the city of Waco, Texas.
Contents
What is the Lake Waco Formation Made Of?
The Lake Waco Formation is mostly made of a type of rock called shale. Shale is a soft, layered rock that forms from mud and clay. It also contains smaller amounts of limestone and layers of volcanic ash. These ash layers are sometimes called bentonites.
Layers Within the Formation
The Lake Waco Formation is divided into three main parts, which scientists call "members":
- The Bluebonnet Member
- The Cloice Member
- The Bouldin Member
Bluebonnet Member Details
The Bluebonnet Member is about 10 to 20 feet (3 to 6 meters) thick. It is made up of tiny broken pieces of inoceramid clams. These are a type of ancient clam. It also contains tiny sea creatures called planktonic foraminifera.
Cloice and Bouldin Members Details
The Cloice Member is about 35 feet (11 meters) thick. It was named after a place called Cloice Branch of the South Bosque River. The Bouldin Member is about 9 feet (3 meters) thick. It was named after Bouldin Creek, near Austin. Both the Cloice and Bouldin Members are made of shales. These shales are rich in organic matter, which means they contain remains of ancient plants and animals. They also have thin layers of limestone and volcanic ash.
Fossils Found in Lake Waco Formation
Scientists have found many amazing fossils in the Lake Waco Formation. These fossils help us learn about the ancient life that lived in this area millions of years ago. Some of the cool fossils found include:
- Plesiosaur remains: Plesiosaurs were large, marine reptiles with long necks.
- Shark's teeth: Showing that sharks swam in these ancient seas.
- Ammonites: These were ancient sea creatures with spiral shells, similar to modern-day nautiluses.
- Inoceramid clams: Large, extinct clams that lived in the Cretaceous seas.
These fossils tell us that the area where the Lake Waco Formation is now was once covered by a sea.
