Aquinnah

My excursion out to Cape Poge took a little longer than I had planned, so I had to race to get to the west end of the island before the sun set. My plans for a long walk on the beach below the bluffs at Gay Head were thwarted by coming darkness, but the view from above was still impressive. And there was no one else there.

Gay Head is an unusual glacial moraine composed of Cretaceous sedimentary rocks (80-100 million years old) thrust upward by the advancing glacier during the Pleistocene. Which makes a pretty neat story, though it sounds like this place also holds many other interesting geologic stories (but none that I was able to deduce from my brief visit). The boulders on the beach below the bluffs are derived from till on the surface. The cobble berm on the beach to the south would also have been fun to spend more time exploring. Sand dunes behind, cobbles on the berm and being pushed into the dune grass, and a sandy beach.

Cape Poge

Chappaquiddick is a small island connected at times to the rest of Martha's Vineyard by the barrier that extends across the southern side of the islands - but it breached during the Patriot's Day Storm (April 07) and remains open. Barrier beaches wrap around the eastern side of Chappaquiddick, extending north to Cape Poge, and then hooking west and south back towards Edgartown. Cape Poge itself is a glacial knob that is sometimes referred to as Natick Island. It is gradually eroding westward and has required the lighthouse to be moved several times. What a bizarre notion - moving a lighthouse instead of building a seawall around it.

Edgartown

Usually lighthouses find themselves creeping towards the sea as the shoreline recedes. Edgartown's Lighthouse has done the opposite - attaching itself to the main island over time as the shoreline accreted. It was built offshore to mark a broad shoal at the mouth of the harbor, with access provided by a trestle. Eventually the trestle was turned into a causeway. Complex sediment dynamics have since filled in much of the area around the lighthouse, forming a remarkably natural looking spit and back barrier wetland. As with many spots in this region, much of the change occurred during the 1938 hurricane - showing such power can build land as well as take it away.

Oak Bluffs

I didn't see any oaks on the bluffs at Oak Bluffs, but have no doubt there may once have been. The low bluffs are now armored with an aging seawall (part of which collapsed this winter). To the south, towards Edgartown, the bluffs give way to State Beach, the long barrier in front of Sengekontacket Pond.

There's more Martha's Vineyard in subsequent posts and at hshipman.