The Chalk Bluffs is a barren

chalk Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor. Cha ...

escarpment An escarpment is a steep slope or long cliff that forms as a result of faulting or erosion and separates two relatively level areas having different elevations. The terms ''scarp'' and ''scarp face'' are often used interchangeably with ''esca ...

in the northeastern part of the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its sove ...

Colorado Colorado (, other variants) is a state in the Mountain states, Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the wes ...

, stretching from the

Wyoming Wyoming () is a state in the Mountain West subregion of the Western United States. It is bordered by Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho to the west, Utah to the southwest, and Colorado to the sou ...

border east of

I-25 Interstate 25 (I-25) is a major Interstate Highway in the western United States. It is primarily a north–south highway, serving as the main route through New Mexico, Colorado, and Wyoming. I-25 stretches from I-10 at Las Cruces, New Mexic ...

to near the

South Platte River The South Platte River is one of the two principal tributaries of the Platte River. Flowing through the U.S. states of Colorado and Nebraska, it is itself a major river of the American Midwest and the American Southwest/ Mountain West. ...

Logan County Logan County is the name of ten current counties and one former county in the United States: * Logan County, Arkansas * Logan County, Colorado * Logan County, Idaho (1889–1895) * Logan County, Illinois * Logan County, Kansas * Logan County, K ...

and

Weld County Weld County is a county located in the U.S. state of Colorado. As of the 2020 census, the population was 328,981. The county seat is Greeley. Weld County comprises the Greeley, CO Metropolitan Statistical Area, which is included in the Denver ...

. Parks.state.co.us: Chalk Bluffs Natural Area
/ref>

Geology

The Chalk Bluffs exposes the Ogallala, Fox Hills and

Arikaree Arikara (), also known as Sahnish,
''Mandan, Hidatsa, and Arikara Nation.'' (Retrieved Sep 29, 2011)

Formation Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondary ...

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent" ...

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', " ...

and

Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch that lasted from about 66 to 56 million years ago (mya). It is the first epoch of the Paleogene Period in the modern Cenozoic Era. The name is a combination of the Ancient Greek ''pal ...

vertebrate fossils are found.

Ecology

Most of the escarpment lies within the

Pawnee National Grasslands Pawnee National Grassland is a United States National Grassland located in northeastern Colorado on the Colorado Eastern Plains. The grassland is located in the South Platte River basin in remote northern and extreme northeastern Weld County bet ...

. As the bluffs are primarily barren and protected from fire. However trees normally found in the foothills of the Rocky Mountains are found there, including:

Ponderosa pine ''Pinus ponderosa'', commonly known as the ponderosa pine, bull pine, blackjack pine, western yellow-pine, or filipinus pine is a very large pine tree species of variable habitat native to mountainous regions of western North America. It is t ...

Rocky Mountain juniper ''Juniperus scopulorum'', the Rocky Mountain juniper, is a species of juniper native to western North America, from southwest Canada to the Great Plains of the United States. Description ''Juniperus scopulorum'' is a small evergreen conifer rea ...

limber pine ''Pinus flexilis'', the limber pine, is a species of pine tree-the family Pinaceae that occurs in the mountains of the Western United States, Mexico, and Canada. It is also called Rocky Mountain white pine. A limber pine in Eagle Cap Wildernes ...

, and

mountain mahogany ''Cercocarpus'', commonly known as mountain mahogany, is a small genus of at least nine species of nitrogen-fixing flowering plants in the rose family, Rosaceae. They are native to the western United States and northern Mexico, where they grow ...

. Numerous

raptor Raptor or RAPTOR may refer to: Animals The word "raptor" refers to several groups of bird-like dinosaurs which primarily capture and subdue/kill prey with their talons. * Raptor (bird) or bird of prey, a bird that primarily hunts and feeds on v ...

s nest on the cliffs including

Swainson's hawk Swainson's hawk (''Buteo swainsoni'') is a large bird species in the Accipitriformes order. This species was named after William Swainson, a British naturalist. It is colloquially known as the grasshopper hawk or locust hawk, as it is very fond ...

ferruginous hawk The ferruginous hawk, (''Buteo regalis''), is a large bird of prey and belongs to the broad-winged buteo hawks. An old colloquial name is ferrugineous rough-leg, due to its similarity to the closely related rough-legged hawk (''B. lagopus''). ...

golden eagle The golden eagle (''Aquila chrysaetos'') is a bird of prey living in the Northern Hemisphere. It is the most widely distributed species of eagle. Like all eagles, it belongs to the family Accipitridae. They are one of the best-known birds ...

s, and

prairie falcon The prairie falcon (''Falco mexicanus'') is a medium-large sized falcon of western North America. It is about the size of a peregrine falcon or a crow, with an average length of 40 cm (16 in), wingspan of approximately 1 meter (40&nb ...

s. The bluffs are a favorite site for

birdwatching Birdwatching, or birding, is the observing of birds, either as a recreational activity or as a form of citizen science. A birdwatcher may observe by using their naked eye, by using a visual enhancement device like binoculars or a telescope, b ...

. It has been recognized by the

National Audubon Society The National Audubon Society (Audubon; ) is an American non-profit environmental organization dedicated to conservation of birds and their habitats. Located in the United States and incorporated in 1905, Audubon is one of the oldest of such orga ...

as a site of "global importance".

Chalk Bluffs Natural Area

A portion of the Chalk Bluffs in

were set aside in September 2001 by the

Colorado State Parks The system of state parks in Colorado integrates outdoor recreation with tourism. There are currently forty-two parks open to the public, and there is one in development. Colorado State Parks host over eleven million visitors each year. Colorado ...

Natural Areas Program as the Chalk Bluffs Natural Area.

Wind farm

The bluffs are adjacent to the

Cedar Creek Wind Farm The Cedar Creek Wind Farm is a 551.3 megawatt (MW) wind farm located about 8 miles east of the town of Grover in north-central Weld County, Colorado. It consists of 397 wind turbines and was constructed in two phases, Cedar Creek I an ...

References

{{coord, 36.47952, -90.16252, type:landmark_globe:earth_region:US-CO, display=title Escarpments of the United States Chalk Landforms of Colorado Nature reserves in Colorado Landforms of Weld County, Colorado Landforms of Logan County, Colorado Protected areas of Logan County, Colorado Protected areas of Weld County, Colorado Neogene Colorado Paleogene Colorado Miocene United States Eocene North America Paleocene North America Eocene paleontological sites of North America Miocene paleontological sites of North America Protected areas established in 2001 2001 establishments in Colorado