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.