Mt. Labrador is one of the most bizarre, beautiful and little known rock formations in North America. The outcrop, which bears an amazing resemblance to the breed that shares its name, is located on a remote section of the southern coast of Maine.
The stunning cliff is an outcrop of Cutler complex anorthosite rock. Anorthosite is a somewhat rare, and quite beautiful, form of intrusive igneous rock and, in an odd twist to our story, a plagioclase mineral called Labradorite is a common constituent of anorthositic rocks.
As igneous rocks cool, well developed systems of joints are generated by the tensile stresses of shrinkage. The high temperature minerals in anorthosites also undergo higher rates of chemical weathering than minerals in low temperature rock types like granite do. This combination of factors means that anorthositic rocks undergo high rates of physical and chemical weathering and are therefore known for eroding into dramatic natural features.
Some other unusual examples of anorthosite outcrops can be found in the Black Giants of New Zealand, parts of the New Jersey Palisades, at Minnesota’s Split Rock lighthouse and – most abundantly – the mountains of the moon.
The billion year old rocks of Mt. Labrador are were first exposed during the Pleistocene glacial period and then later modified by digital erosion.
Popular largely only with mountain climbers, Mt. Labrador doesn’t attract many other visitors because of it’s remote location — about 50 miles west of Portland and 50 miles away from anything else.