MAMassachusetts Geography

Cape Cod is a pile of ice age debris

Cape Cod, Martha's Vineyard and Nantucket are not bedrock. They are sediment the Laurentide Ice Sheet bulldozed ahead of itself and then dropped when it stalled roughly 20,000 years ago. The Sandwich Moraine forms the Cape's spine from the mainland out toward Orleans, the Buzzards Bay Moraine runs down its western shoulder, and the flat outwash plain between them is where the ponds sit. Every one of those kettle ponds, and there are more than 300 on the Cape alone, is a hollow left by a stranded block of ice that melted in place. The hooked arm curling north to Provincetown is younger than the rest: waves have been carrying sand up the outer shore ever since the ice pulled back, and the tip is still lengthening.

Since 1914 the Cape has been an island in the strict sense. The Cape Cod Canal cuts 17.4 miles across the isthmus at Bourne and Sandwich, and after the Army Corps of Engineers widened it between 1935 and 1940 it became the widest sea level canal in the world at 480 feet. Three crossings span it, two highway bridges and a vertical lift railroad bridge. Cape Cod National Seashore, signed into law by John F. Kennedy in 1961, protects about 40 miles of the outer beach, including the Wellfleet and Truro cliffs where the Atlantic shaves several feet off the outwash plain in an average year.

Sea level to the Taconic ridge in 50 miles

Massachusetts covers 10,554 square miles, 44th among the states, and roughly a quarter of that figure is water. Its high point, Mount Greylock at 3,489 feet above Adams, is not in the Berkshires proper but in the Taconic Range hard against the New York line. Greylock holds the only boreal spruce and fir forest in the state, a pocket of subarctic habitat stranded at elevation when the climate warmed. The Veterans War Memorial Tower on the summit, a 93-foot granite shaft lit like a lighthouse beacon, went up in 1932.

Travelling west to east the state crosses five distinct belts: the Taconics, the Berkshire Hills of the Western New England Upland, the Connecticut Valley Lowland, the Eastern New England Upland, and the Coastal Lowland holding Boston and everything seaward of it. The Connecticut Valley is a rift basin, a crack that opened as Pangaea pulled apart, which is why it holds soft red sandstone and dinosaur trackways rather than the hard schist and gneiss standing on either side of it.

Four towns under the Quabbin

Boston needed water and the Swift River valley had it. Dana, Enfield, Greenwich and Prescott were disincorporated on 28 April 1938, their buildings burned or moved, their cemeteries relocated to Quabbin Park Cemetery in Ware. Winsor Dam and Goodnough Dike sealed the valley, and filling took from 1939 to 1946. The Quabbin Reservoir now holds 412 billion gallons across 39 square miles with 181 miles of shoreline, and the water reaches greater Boston 65 miles east entirely by gravity through the Quabbin Aqueduct and the Wachusett Reservoir. Nothing is pumped. The old road grades, stone walls and cellar holes are still legible on the shoreline when the water level drops.

The notch Connecticut kept

In 1642 Massachusetts hired Nathaniel Woodward and Solomon Saffery to run its southern boundary. Rather than survey overland they sailed around Cape Cod and up the Connecticut River, then worked inland, and set the line roughly four to seven miles too far south. Connecticut and Rhode Island disputed it for more than 150 years. The 1804 settlement handed Connecticut a rectangle about two and a half miles wide out of the town of Southwick, which is why the southern border of Massachusetts drops abruptly around the Congamond Lakes and then steps back up. The jog is still there on every map.

Five states touch Massachusetts: New York, Vermont, New Hampshire, Connecticut and Rhode Island. Almost every drop of rain that falls on the state reaches the sea off New England, through the Merrimack, the Charles, the Taunton or the Connecticut. The exception is the far northwest corner of Berkshire County, where the Hoosic River runs north into Vermont, turns west into New York and joins the Hudson at Stillwater, so that corner's water leaves through New York Harbor instead.

Both temperature records in one hill town

Chester, a Berkshire foothill town of about 1,300 people, holds each end of the Massachusetts thermometer. It hit 107 F on 2 August 1975, tying New Bedford on the same day, and fell to minus 35 F on 12 January 1981. That 142-degree range in a single small town says most of what needs saying about interior New England. On the water it is a different state: Nantucket, 30 miles offshore, has a growing season weeks longer than the Berkshires and rarely sees the same extremes because the surrounding ocean damps them. Blue Hill Observatory in Milton, on a 635-foot summit, has recorded conditions continuously since 1885, the longest unbroken weather record in the United States.

The state has 192 miles of general coastline, but trace every harbour, inlet and island edge and the tidal shoreline runs to 1,519 miles. Nor'easters, not hurricanes, do most of the coastal damage, and the worst of them push water into the funnel of Massachusetts Bay at high tide.

Common questions about Massachusetts geography

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