The Book Cliffs are a series of mountains and cliff

Cliff

In geography and geology, a cliff is a significant vertical, or near vertical, rock exposure. Cliffs are formed as erosion landforms due to the processes of erosion and weathering that produce them. Cliffs are common on coasts, in mountainous areas, escarpments and along rivers. Cliffs are usually...

s in western Colorado

Colorado

Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...

 and eastern Utah

Utah

Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...

, in the western United States. They are so named because many of them have the triangular appearance of a book that has been opened up, then turned on its sides and set to rest on the open sides of the book, on a table.
Stretching nearly 200 miles from east to west, the Book Cliffs begins where the Colorado River descends south through De Beque Canyon into the Grand Valley

Grand Valley (Colorado)

The Grand Valley is an extended populated valley, approximately 30 miles long and 5 miles wide, located along the Colorado River in Mesa County in western Colorado and Grand County, Utah in the United States. The valley contains the city of Grand Junction, as well as other smaller communities...

 (near Palisade, Colorado

Palisade, Colorado

Palisade is a Statutory Town in Mesa County, Colorado, United States. It is part of the Grand Junction Metropolitan Statistical Area. The population was 2,692 at the 2010 census....

) to Price Canyon (near Helper, Utah

Helper, Utah

Helper is a city in Carbon County, Utah, United States about 120 miles southeast of Salt Lake City and northwest of the city of Price. It is also known as the "Hub of Carbon County". The population was 2,025 at the 2000 census....

).