How was Pierre shale formed?

How was Pierre shale formed?

The Pierre Shale is of marine origin and was deposited in the Western Interior Seaway. It is correlative with other marine shales that occur farther west, such as the Bearpaw Shale, Mancos Shale and the Lewis Shale. Most of the formation was deposited in the Campanian Age of the late Cretaceous.

How old is the Pierre Shale formation?

Pierre Shale, division of Upper Cretaceous rocks in the United States (the Cretaceous Period lasted from about 146 million to 65.5 million years ago). Named for exposures studied near old Fort Pierre, S.D., the Pierre Shale occurs in South Dakota, Montana, Colorado, Minnesota, New Mexico, Wyoming, and Nebraska.

How did the Niobrara Chalk formation form?

The chalk formed from the accumulation of coccoliths from microorganisms living in what was once the Western Interior Seaway, an inland sea that divided the continent of North America during much of the Cretaceous. It underlies much of the Great Plains of the US and Canada.

When was the Pierre Shale unit deposited?

70-80 million years ago
The Pierre Shale is the youngest Cretaceous unit in the state of Nebraska. It was deposited during the Campanian and Maastrichtian (~70-80 million years ago).

What is the name of the body of water in which the Pierre Formation was deposited?

The Pierre Shale, which forms the bottommost layer of the park’s geology, was deposited 75-69 million years ago. It was laid down by a shallow inland sea known as the Western Interior Seaway.

What rock is chalk?

Chalk is a soft white limestone made from the microscopic skeletons of marine plankton.

Is Niobrara a shale?

2.22 Niobrara Shale The Niobrara shale formation (Denver-Julesburg Basin, Colorado) is a shale rock formation located in Northeast Colorado, Northwest Kansas, Southwest Nebraska, and Southeast Wyoming. Oil and natural gas can be found deep below the earth’s surface at depths of 3000–14,000.

Was Western US underwater?

Up to half of the continent’s modern surface area may have been submerged by this sea. This is called the Western Interior Seaway. It covered the majority of states like Texas, New Mexico, Oklahoma, Colorado, Kansas, Nebraska, the Dakotas, and Wyoming.

How deep was the inland sea in North America?

2,500 feet
The Western Interior Seaway was a huge inland sea. It split North America into two halves for most of the mid- and late-Cretaceous Period. It was up to 2,500 feet (760 m) deep, 600 miles (970 km) wide and over 2,000 miles (3,200 km) long.

Can we eat chalk?

While chalk is minimally toxic, not poisonous in small amounts, and may not hurt you, it’s never a good idea to eat chalk. A pattern of eating chalk is a different story, however. Eating chalk often can disrupt your digestive system and cause damage to your internal organs.

Is chalk man made?

Chalk Characteristics and Properties Chalk, in both its natural and man-made form, is white in colour and is considered to be a fairly soft solid. Naturally, It comes from the ground where it is found as a porous (can hold water) sedimentary rock. It is a form of limestone and is composed of the mineral calcite.

Where is the Eagle Ford Shale?

The Eagle Ford Shale is a hydrocarbon-producing geological formation extending over 26 counties. It stretches from the Mexican border between Laredo and Eagle Pass up through counties east of Temple and Waco.

What is the stratigraphy of the Pierre Shale?

STRATIGRAPHY The Pierre Shale is underlain by the calcareous Niobrara Formation and overlain by the Fox Hills Sandstone. Both contacts are conformable and transitional. The base of the Pierre is at the top of a persistent orange-weathering chalk bed that forms a hogback at the top of the Smoky Hill Shale Member of the Niobrara Formation.

Where are the Pierre shale deposits in Colorado?

The Pierre Shale is the host formation for commercial oil deposits in the Florence and Canon City fields in Fremont County, Colorado, and the Boulder Oil Field in Boulder County, Colorado.

When did Meek and Hayden describe Pierre Shale?

The Pierre Shale was described by Meek and Hayden in 1862 in the Proceedings of the Academy of Sciences (Philadelphia). They described it as a dark-gray shale, fossiliferous, with veins and seams of gypsum, and concretions of iron oxide.