While the Catskill Mountains are called mountains, they are technically classified as plateaus or highlands.

Here's why:

* Formation: The Catskills were formed by erosion, not volcanic activity or tectonic plate collisions like most mountain ranges. Over millions of years, glaciers carved away the top layers of an ancient plateau, leaving behind the rounded peaks and valleys we see today.

* Elevation: The Catskills have a significantly lower average elevation than true mountain ranges. The highest peak, Slide Mountain, reaches 4,204 feet, while many mountain ranges have peaks over 10,000 feet.

* Shape: Catskill peaks are generally rounded and smooth due to erosion, unlike the sharp, pointed peaks found in true mountain ranges.

So, while the Catskills are often referred to as mountains, they are technically a dissected plateau or highland. This doesn't make them any less beautiful or enjoyable to explore, though!