The Geologic Story of the Beehive

Beehive over Sand Beach
Beehive over Sand Beach as seen from the Great Head Trail.

NPS / W. Greene

Visitors taking on the challenge of hiking the Beehive, or even those who contemplate it from the comfort of Sand Beach or the Park Loop Road, can note its distinctive shape. The famous iron rungs and ladders ascend the sheer cliffs of the south face of the peak. This shape provides clues to the geological processes that have shaped Acadia National Park and that give such varied recreational opportunities.

The Beehive is a fine example of what geologists call a rouche moutonnée. This French term was coined by Swiss geologist Horace-Bénédict de Saussure during explorations of the Alps in 1786. Although these explorations predated modern glacial theory, de Saussure noted that many of the rocks he saw had distinctive smooth surfaces and applied the term. Later geologists determined that these peaks had been smoothed by the grinding process of glaciers passing across the surface.
Drawing showing glacial ice moving over a mountain and plucking off boulders
Diagram showing the glacial formation of a rouche moutonnée.

NPS / M. Reading

Asymmetrical peaks (steep on one side and more gradual on the other) like the Beehive were formed by a process of glacial erosion known as “glacial plucking.” This happens when a glacier slides across a pre-existing peak (in the case of the Beehive and other peaks in Acadia, from north to south). The glacier smooths the northern side and the pressure of the overlying ice past the peak causes larger chunks of the southern side to break off. Geologists are able to look at the Beehive and determine the direction that glaciers were travelling, even though the glaciers disappeared from the region over 10,000 years ago. Once you’re familiar with the shape, you can spot these distinctive features elsewhere in Acadia! South Bubble and the Porcupine Islands are other great examples!

So what does rouche moutonnée mean? Rouche is French for “rock” and moutonnée is derived from the French mouton, meaning “sheep.” Many geologists simply translate it as “sheepback or sheep-like rock.” But de Saussure may have had something more specific in mind. In his notes, he describes the rounded rocks as resembling a thick mane of hair or wig, which he terms moutonnée. This hairstyle, popular in France at the time, consisted of a swept up front and a gradually tailing off back and was often held in place with sheep fat!

Whether you imagine the peaks of Acadia as a herd of gently grazing sheep or a group of sophisticated 18th century Europeans, just know that you’re looking at the glacial history of Acadia National Park!

Acadia National Park

Last updated: September 21, 2021