The Catskill Mountains, an area in New York State

New York

New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...

 northwest of New York City

New York City

New York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...

 and southwest of Albany

Albany, New York

Albany is the capital city of the U.S. state of New York, the seat of Albany County, and the central city of New York's Capital District. Roughly north of New York City, Albany sits on the west bank of the Hudson River, about south of its confluence with the Mohawk River...

, are a mature dissected plateau

Dissected plateau

A dissected plateau is a plateau area that has been severely eroded so that the relief is sharp. Such an area may be referred to as mountainous, but dissected plateaus are distinguishable from orogenic mountain belts by the lack of folding, metamorphism, extensive faulting, or magmatic activity...

, an uplifted region that was subsequently eroded into sharp relief

Terrain

Terrain, or land relief, is the vertical and horizontal dimension of land surface. When relief is described underwater, the term bathymetry is used...

. They are an eastward continuation, and the highest representation, of the Allegheny Plateau

Allegheny Plateau

The Allegheny Plateau is a large dissected plateau area in western and central New York, northern and western Pennsylvania, northern and western West Virginia, and eastern Ohio...

. They are sometimes considered an extension of the Appalachian Mountains

Appalachian Mountains

The Appalachian Mountains #Whether the stressed vowel is or ,#Whether the "ch" is pronounced as a fricative or an affricate , and#Whether the final vowel is the monophthong or the diphthong .), often called the Appalachians, are a system of mountains in eastern North America. The Appalachians...

 into Upstate New York

Upstate New York

Upstate New York is the region of the U.S. state of New York that is located north of the core of the New York metropolitan area.-Definition:There is no clear or official boundary between Upstate New York and Downstate New York...

, although they are not geologically related. The Catskills are west of the Hudson River

Hudson River

The Hudson is a river that flows from north to south through eastern New York. The highest official source is at Lake Tear of the Clouds, on the slopes of Mount Marcy in the Adirondack Mountains. The river itself officially begins in Henderson Lake in Newcomb, New York...

 and lie within the bounds of six counties (Otsego

Otsego County, New York

Otsego County is a county located in the U.S. state of New York. The 2010 population was 62,259. The county seat is Cooperstown. The name Otsego is from a Mohawk word meaning "place of the rock."-History:...

, Delaware

Delaware County, New York

Delaware County is a county located in the U.S. state of New York. As of 2010 the population was 47,980. The county seat is Delhi. It is named after the Delaware River, which was named in honor of Thomas West, 3rd Baron De La Warr, appointed governor of Virginia in 1609.-History:When counties...

, Sullivan

Sullivan County, New York

Sullivan County is a county located in the U.S. state of New York. As of the 2010 census, the population was 77,547. The county seat is Monticello. The name is in honor of Major General John Sullivan, who was a hero in the American Revolutionary War...

, Schoharie

Schoharie County, New York

As of the census of 2000, there were 31,582 people, 11,991 households and 8,177 families residing in the county. The population density was 51 people per square mile . There were 15,915 housing units at an average density of 26 per square mile...

, Greene

Greene County, New York

Greene County is a county located in the U.S. state of New York. Its name is in honor of the American Revolutionary War general Nathanael Greene. Its county seat is Catskill...

, and Ulster

Ulster County, New York

Ulster County is a county located in the state of New York, USA. It sits in the state's Mid-Hudson Region of the Hudson Valley. As of the 2010 census, the population was 182,493. Recent population estimates completed by the United States Census Bureau for the 12-month period ending July 1 are at...

).