Bushnell Rock Member facts for kids
Quick facts for kids Bushnell Rock FormationStratigraphic range: Middle Eocene |
|
|---|---|
| Type | Formation |
| Unit of | Lookingglass Formation |
| Sub-units | Tenmile Member, Olalla Creek Member |
| Lithology | |
| Primary | Basal Conglomerate |
| Other | Sandstone Beds |
| Location | |
| Coordinates | 43°07′33″N 123°36′55″W / 43.1259462°N 123.6153677°W |
| Region | Douglas County, Oregon |
| Country |  United States |
| Type section | |
| Named for | Bushnell Rock |
| Named by | Ewart M. Baldwin (U of O Geo Dept) |
The Bushnell Rock Formation is a special type of rock layer. It got its name from a visible part of the rock called Bushnell Rock. A geologist from the University of Oregon, Ewart M. Baldwin, named it in 1974.
This rock formation, along with the Tenmile Member and Olalla Creek Member, forms a bigger rock unit called the Lookingglass Formation. You can find these rock layers under the Lookingglass Valley in Douglas County, Oregon.
What is the Bushnell Rock Formation?
The Bushnell Rock Formation is mostly made of a type of rock called basal conglomerate. This means it's a rock made from many different kinds of smaller, rounded rocks cemented together. It also has some layers of sandstone, but these are rare.
This rock layer was formed when an ancient sea slowly spread over the land. This process started during a time called the Paleocene Epoch. But most of the rock was formed later, during the early Eocene Epoch. These are periods in Earth's history, millions of years ago.
What is it Made Of?
The conglomerate rock in this formation is quite interesting!
- About 70% of it is made of small rock pieces.
- 60% of these pieces are from sedimentary rocks.
- 30% are from metamorphic rocks.
- 10% are from volcanic rocks.
- These rock pieces are usually about 1 to 2 inches (2.5 to 5 cm) wide.
- The other 30% of the rock is a "matrix." This is like the glue that holds the rock pieces together. It's made of medium to coarse sand.
It's hard to measure the exact thickness of the Bushnell Rock Formation because it's not exposed in many places. In one spot, it was found to be at least 5 meters (about 16 feet) thick. But in other areas, where it touches the Olalla Creek Member, it might be as thick as 100 meters (about 328 feet)!
Are There Fossils?
Sometimes, conglomerate rocks can contain fossils. However, these fossils are usually found inside the smaller rock pieces that make up the conglomerate. The Bushnell Rock Formation is not known for having many fossils.
