It was not a group of lemmings that were observed at the Gay Head Cliffs last Sunday.
And, not to worry: no one was about to launch themselves to their death. (The lemming suicide legend is a myth, by the way, but that is a story for another time.) The group in question began at the bottom of the cliffs, rather than 150 feet up at thetop. Martha’s Vineyard Land Bank ecologist Julie Schaeffer had coaxed us out for a stroll on a truly splendid spring day for camaraderie and geology.
On a visit to the Gay Head Cliffs, a National Historic Landmark, you truly step back in time. All the way back, in fact, to the Cretaceous Period, which was over 135 million years ago during the age of thedinosaurs. It was then that some of the oldest sediment layers found in the cliffs were laid down.
The ancient sediments were gradually deposited on top of the existing continental shelf, sometimes when this land was underwater and sometimes when it was dry, before the most recent ice age about 15,000 years ago. It was then, during this ice age, that giant glaciers advanced and retreated, pushing and folding the layers of sediment like ribbon candy, and at the same time creating the Island of Martha’s Vineyard.
The old folded layers of ancient sediments at the cliff eventually mixed with new layers of soil that were deposited on top of the older sediments. Sand, too, was deposited by wind and water (the water that came with the glaciers and was left behind after their retreat). Thus, the Gay Head Cliffs can boast that they contain the oldest sediments on the Island — surprisingly enough, even older than the Island itself.
The mixing of old and new is impressive, but the cliffs add color to the story. Streaks of red, white, green and black can be found on the face of the cliffs where large deposits of clay create a sediment stream.
The Moshup myth explains that the red clay was the stain from the blood of whales that he beat against the cliffs to kill them. Science says that the red deposits result from iron oxide in the clay. These clays were used to make the bricks that built the Gay Head Light. Today it is illegal to remove clay or any material from the cliffs, so admire their remarkable visage from a distance — let the cliffs touch you; don’t touch them.
Green clays can also be found here. The green contains minerals and glauconite and is where many of the marine fossils may be found. White clays result from particles of quartz, while the black color comes from lignite.
Julie noted that perhaps the best time to visit the Gay Head Cliffs is during a rainstorm, when you can almost watch the cliffs melt. And they actually are melting; the cliffs are notable for their rapid rate oferosion. Over two feet of cliff are lost annually.
Another interesting feature is the land the cliffs rest on — the beach itself. In the winter and spring it is a very rocky shoreline, but by some miracle (well, really, just the force of deposition), it becomes a sandy beach comesummer. This is fortunate for all of those beachgoers who flock to this site, which has deservedly been listed as one of the top beaches in the co untry.
Whole volumes could be written about the rich history of the Gay Head Cliffs, but to give you the cliff notes version, Julie’s description was one of a landscape both old and new; one of permanent change and changing permanence.
Suzan Bellincampi is director of the Felix Neck Wildlife Sanctuary in Edgartown.