Boston Hollow is a deep ravine in Ashford, Connecticut. It is a unique location in several ways. In geological terms it is an ancient fault in the Central Maine Terrane of the eastern highlands of Connecticut. More specifically, it lays within the Bigelow Brook Formation which consists of high grade pelitic schists and gneisses. Although there are many faults in this region, none is as deeply cleft, well pronounced, nor well preserved as this hollow. Accessibility Boston Hollow is approached from the southwest, from Westford, by unpaved Boston Hollow Road. This is a portion of the historic Center Turnpike, constructed in 1827, that was formerly a major route from Boston to Hartford. The road follows a nearly straight course through the bottom of the hollow beside a little, unnamed brook for about two thirds of its passage. Then the brook peters out and a height of land is achieved. Continuing along the road towards the northeast, another swath in the ground forms but this is rarely filled with water. The second gully leads into a swamp at the end of the hollow. Near the end of the hollow a ten-acre (4 ha) parcel of land is situated. This land has an inactive gravel pit against the hollow wall. The only house in the area is located just past this land. The brook and the second swath as well as the house and the private land are all on the west side of the hollow. Geography The geography of Boston Hollow is characterized by the deep fault-cleft running almost perfectly straight in the northeast direction. The basement of the hollow is approximately above sea level at the southern head, and at the swamp at the northern exit. The height of land is about above sea level. The hollow defined by the distance the road passes through its bottom is nearly long. The elevation change through the bottom of the hollow is therefore quite gradual. The width of the base from wall to wall varies from . On the west side there are swampy and stagnant wetlands through much of the course of the hollow brook as the water flow is too little and the incline is too slight to adequately drain the area. On either side of the low land the walls of the hollow rise swiftly. On the west side they rise most steeply to a height of about .