ICE, SAND AND SEA
“Cape Cod is a geological oddity. It does not look like any other section of the American continent, even to an amateur physiographer who doesn’t know a terminal moraine from a trilobite. What is the secret of this curious and attractive topography that strikes you at first glance when you cross the high steel arch over the Canal at Buzzards Bay?
In the first place, the scale of the Cape is small. It is only a little over twenty miles wide at its widest point, at Barnstable it is six miles across, two from sea to sea at Truro, and less than a mile at Provincetown, where you can see two oceans as you drive. Here the whole gigantic process of geology is visible on a diminished scale, just as by a reverse process cell structure can be seen through a microscope.
From the monument at Provincetown, from Signal Mill in Bourne, from the high sweet-smelling moors of Truro you can see nearly the whole circuit of the Cape and draw a pretty good map of it just from the view.
Cape Cod is a narrow glacial peninsula, running 40 miles out to sea, its frail and perishable coast of sand cliffs and earth continually crumbled and torn down by the wind and the pounding ocean, but it is anchored to the bottom of the world by rock and a pre-glacial clay foundation that is one of the ‘ancient drainage divides of the country.’ Over this the glaciers piled hills and dug valleys, spread and raked a top-dressing of sand and debris that in time became the ‘fat and lustie’ soil that Bradford speaks of.
Fingerprinting glaciers is still not an exact science, but roughly speaking it was 35,000 years ago that the great ice floe from the north poured thickly over New England, thrusting a hundred miles out into the ocean. At the southeastern end the ice field split into huge thumb-shaped projections called lobes. One of these lobes, the Buzzards Bay glacier, lay along the eastern shore of Buzzards Bay and north along the Massachusetts coast. Next to it on the east the Cape Cod glacier filled Cape Cod Bay. Geologists hypothecate a third glacier called the South Channel glacier, part of a vast ice field reaching down from Maine to Nova Scotia. The wicked shoals of Nantucket and Georges Banks may be the submerged terminal moraines of this glacier. Its pack pushing west helped to block out the land between Chatham and Highland Light, and there are about a dozen parallel valleys in Eastham, Truro and Wellfleet whose floors run from east to west. The simplest explanation of them is that ice rivers flowed out from the South Channel glacier on the west scoring these valleys that are now so sunny and green.
Together the glaciers moved southward, spreading out right and left as they crawled on. They scraped and pushed ahead of them huge heaps of debris, piled it up in front of and between their edges, finally melted away and left it there in the form of the moraine hills that run from Buzzards Bay down to Woods Hole and Falmouth, and bending. eastward through Sandwich along the bay shore, continue through the northern parts of the coast villages through Orleans to the sea.
These ridges of high ground are true terminal moraines, and nice ones too. Pine woods cover them, their sides slope gently down to a great plain. This, the whole South Shore, meadows, little valleys, green marshes cut by blue strips of sea, is an outwash plain, made by glacier rivers flowing out from under the ice, spreading and leveling the surface like frosting on a cake. The plain is starred with shining lakes and ponds (270 of them) and pitted with countless deep hollows called kettle holes. These are glacial too, the marks of huge ice blocks which were left by old glaciers in depressions, buried under earth by new glaciers, but finally melted and sank, caving into pockets which were sometimes filled with the seepage of ground water, or merely made deep dimples in the ground. There are thousands of them from Woods Hole to Truro, and they are found by sounding under water. One, near Woods Hole, is 120 feet deep.
Scattered like nuts in the frosting are occasional great chunks of rock. These are not part of the backbone of Cape Cod, but are ‘drift boulders’ dragged by glaciers from north- ern New England or New Hampshire or Canada. Even Plymouth Rock is not a native, but comes from Boston.
The most notable examples of these are Enos rock on the Nauset moraine in Eastham, 34 feet long, the Indian Prayer Rock at West Brewster, Great Rock, 400 tons, at Bourne, and a 12-foot boulder near Highland Light. There is a foreign settlement of rocks called ‘Bear’s Den’ in Falmouth, west of Falmouth village, and also ‘Devil’s Den’ in Pocasset.
There are no very sensational heights on the Cape, but there are some respectable summits. Bourne Hill in Sandwich is the highest, nearly three hundred feet, but there is no driving road to the top and no real view. A road leads up to Pine, or Signal Hill, in Bourne, however, with a fine prospect at the top. Scargo Hill in Dennis has a tower with an eighty-mile glance around the Bay. Shoot-Flying Hill in Barnstable is called so because it is said to be a vantage point for shooting wild fowl. Manomet Hill in Plymouth is the highest landmark of them all. In colonial days these hills were used to signal from, fires by night and smudges by day.
He who walks may read all this glacial history of the Cape, and it is pleasant summer reading, but there is a more dramatic story along the shore.
No man saw the paralyzed earth stir slowly to life when the glaciers weakened. For only three hundred years has history checked this coast and three hundred years is a short time for observation when the sea has been working away for centuries, leveling and smoothing the rough shore, tearing down cliffs, wrecking old harbors and cutting out new. The waves have completely washed away Nauset Island, where Leif Ericsson is thought to have landed about 1003. It lay between Chatham and Eastham, and a long point ran out into the Atlantic. There was a shoal rip on the northeast side which gave Gosnold in 1602 such a scare that he called it ‘Tucker’s Terror,’ and the point which took very tricky sailing to round he called Point Care.
All this is gone now, the sea works fast, and Cape Codders have seen great changes in their own time. The shore line is continually shifting, shoals and harbors come and go, and the United States Coast Guard Survey must revise its maps every few years. The waves sweep north and south, The shore of Cape Cod is largely composed of sand cliffs and earth which are continually being crumbled and eaten away by tempest and ocean wave. These dunes, etched by the wind, are at Barnstable. slanting into the shore, and this carpenter work has cut back the head of the Cape and added regular Cape Cod additions or lean-tos right and left. The sand ‘walks,’ the bones of ancient ships are buried for years and dug up again, the whole coast moves and shudders with the endless stir of the sea.
It was this ‘variable and inconstant’ shore that made our ancestors think the whole of Cape Cod was perhaps only a hieroglyphic of sand, written by the sea, doomed to be rubbed out by the sea.
Only ten miles of this is true. The old glacial Cape ends at High Head at Truro. From there to Long Point at Provincetown is made land, made out of the wreckage of the old cliffs and shore of material torn away from the coast of Truro and Wellfleet and Eastham.
The Cape is constantly narrowing as the sea pulls down the shore and sweeps its winnings north and south. The piled-up shoals grow and rise above the water, winds blow the top into dunes, beach grass springs up and ties the sand down. So the line of shoals beyond Truro finally joined the mainland. Peaked Hill Bar is now in the making and will some day rise from the ocean and join the dunes of the Back Shore. Only a hundred years ago Race Run was a free salt river, splitting the Race off from the mainland; now it is silted up and built solid into the land.
This process of destruction and repair goes on forever. If you stand on the Clay Pounds at Highland Light in a northeast gale and watch the surf bite out the base of the cliff, you wonder how long before the waves will eat clear across the mild hills at Truro and make an island of Provincetown. Geologists say the shore recedes on an average about three feet a year. Peaked Hill Coast Guard Station has been moved twice and its old brick foundations are now part of the beach; at Pamet a long line of cottages has been dragged back several times after almost toppling into the sea. Chatham had lost four hundred feet of ground and two lighthouses by 1879. At Nauset Light four lighthouses have been built to avoid the encroachments of the waves. It is difficult to deny the sea once it launches its attack against the shore.
But the sea is freakish and unpredictable and it builds up new beaches and harbors out of the ruins of the old. Instead of destroying the old glacial shore of Eastham, it has thrown up the fifteen-mile barricade of Nauset beach and given Eastham a small harbor, though the harbor will not stay put and has now moved over to Orleans. Southward this clear reach of sand goes on to make the magnificent stretches of Monomoy which extend miles south of Chatham and this is all young, land robbed from Chatham and Orleans. Monomoy Point is growing and its shoals push out toward Great Point, the northeast end of Nantucket. But a great scour of current will probably always keep this entrance to Nantucket Sound open.
So on the Bay Shore. The high dunes of Sandy Neck are an extension of Spring Hill beach and protect the old inner shore of Barnstable, also giving it a harbor. True, the neck is stretching across the harbor toward Dennis, and the channel of Barnstable Harbor is filling up, but the tide rushes in more powerfully as it contracts and may keep it clear. On the Bay Shore, too, the waves have cut back the cliffs of Truro and Wellfleet and leveled and polished the fine beaches that run clear to Provincetown. But at Pamet River, which was once a good harbor with even a lighthouse, the channel is filling up with marsh and is a harbor no more.
Bound Brook Island at Wellfleet, Great Island and Griffith’s Island were once real islands lying free in Cape Cod Bay. Now they have been puttied together with sand and marsh till they are one — but just to be different the sea has cut away Billingsgate from its logical chain, and left it a sand bar with a run of shallow water between it and the end of what used to be Great Island.
As for the delicate and perishable hooked spit that makes Provincetown Harbor one of the best in the world, it is more sturdy than it looks. This also was built of stolen material, loose masses of earth and gravel torn from the old shore, driven northward and washed westward by winds and currents. These same forces feed and reinforce it continually, making the thin whiplash of land that swings round from the dunes and seems to lie so lightly on the surface of the sea that it looks like a mirage. But notice that its tip points northeast. Throw a bottle out on the Back Shore. You may find it at Long Point.
East Harbor — it does not look like a harbor now but merely a largish pond — which you pass on the Beach Point road to Provincetown was once open salt water, a long spit running far back with only a strip of marsh between it and the ocean beach. At one point it was only five rods wide at high water and the sea threatened to break through in any gale and shovel a tidal wave of sand into Provincetown Harbor. Provincetowners, already fighting sand which was blowing over their houses, were alarmed by this into several makeshifts — beach grass, a bridge, a fence — finally, in 1869 an expensive dyke which was 1400 feet long. It destroyed East Harbor, but it saved Provincetown harbor and the town.
At Long Point, too, sand washed around from Race Point into the harbor, where it set to work building flats, but the government stopped this with wooden bulwarks. In 1911 the great breakwater was thrown across from the west end to Long Point and now Provincetown Harbor stands firm.”