Boston’s Basin

The Boston Basin is the geological description of the area where the city is situated, a depression of land bordered on three sides by higher ground forming a rim that extends from the Fellsway in the north (“Fells” is a Saxon word meaning “rocky, hilly, tracts of land”), to the rocky suburbs west of the city, including Arlington Heights and the Prospect Hill area in Waltham, and the Blue Hills in the south. The basin formed millions of years ago when a mixture of volcanic rock, slate, and gravel was depressed by the heavier surrounding rock. This land surface is on a rift between two very small tectonic plates, once covered by ocean waters and later by glacial melt.

Highway 128/I-95 follows this rim around Boston proper, and driving west on Route #2, while passing between two steep granite cliffs, a driver can see from a fairly good height Boston nestled in its basin. The Boston Basin can also be viewed from west of the city on Prospect Hill at Totten Pond Road in Waltham. To the south of Boston, look at the city in the distance after climbing up the Great Blue Hill on a tract of land preserved over a hundred years ago for public enjoyment by the Trustees’ of Reservation.

Boston because of its geography is a relatively small city of forty-eight square miles with a population that averages around 650,000. The founders in 1630 arrived at a place that was even smaller – a small, tadpole-shaped peninsula barely connected to the mainland by a narrow strip of land the English colonists called the “Neck” that was often washed by the tides. In fact, over the next couple of centuries, the enterprising citizens of Boston sought to expand their land by building wharves to extend out into the harbor and by filling in coves and small ponds with gravel from nearby hills. In fact, Beacon Hill lost a good part of its mass with these projects, and two other hills next to it – Mounts Pemberton and Vernon were mostly leveled. For those of you who are new to Boston, Back Bay was just that – a bay – that was filled in the mid-1800s with gravel that came all the way by train from the town of Needham. In fact, one of my friends who lives there, remarked recently that when she was in Copley Square, she was standing on part of Needham.

The Charles River Basin, on the other hand, is the man-made pond between Cambridge and Boston created in the early 1900s by the damming of the river where the Museum of Science is located. Around the turn of the nineteenth century urban planners had set up a series of wooden panels for the purpose of holding back the tidal salt water that would mingle with the river water then flow back during low tide, leaving behind unhealthy foul-smelling water. Since the panels were not very effective, the Charles River dam was built to replace them in 1910. Before the larger Gridley Dam was completed in 1978, I recall as a member of Community Boating, Inc., where I learned to sail, that day trips were planned to pass from the river basin, to the dam and through the locks, before going out into harbor. Today small pleasure craft now move beneath the Zackim Bridge, through the locks at the Gridley Dam, and out into the harbor through the small parks and green spaces that have replaced what was once a depressed mile-long channel area. You can see the narrow channel of the 1910 dam by standing along the sidewalk in front of the Museum of Science, just to the left of the dinosaur statue.

Where in earlier centuries, the river had been somewhat “contained” upriver by building dams that were high enough for the falling water to power mills for sawing, grinding grain, and weaving textiles, the Charles River Basin is an example of the river being contained for sanitary and aesthetic reasons while creating a pleasurable oasis in the city. The park that borders the basin was the work of city planners and landscape architects, including Charles Eliot and his mentor Frederick Olmsted, who were aware of the importance of park lands and green places for urban dwellers and workers of the new industrial revolution.

Note: John Hanson Mitchell’s The Paradise of All These Parts where I found out more about Boston’s basin is a great read if you enjoy history with a little bit of geology mixed in. He also writes with a great sense of humor.