GEOLOGY

The vast mountain ranges characteristic of the Gates of the Arctic National Park and Preserve were initially formed through the transportation and uplifting of crust through plate tectonics as well as volcanic activity continuously building granite at the surface. Over millions of years, glaciers further carved out the shapes of these landforms, making them into the peaks we see and appreciate today.

The Arrigetch Peaks are one of the many peaks in the park formed by magma cooling into granite and being uplifted by tectonic activity. Other mountains include Frigid Crags and Boreal Mountain, which are the two peaks the park was named after.

As previously mentioned, many of the park's mountains are made of granite, which is a type of igneous rock.

Often surrounding the mountains are schist belts, or belts of metamorphic rock.

Most of the park is built upon sedimentary rocks once part of the ocean floor, known as the Endicott Group.