 After preliminary exploration by members of the New York State Archaeological Association in the 1940s, Grassmann identified post molds of a stockade line, pinpointing the location, and led the thorough exploration of the site of Caughnawaga from 1950 to 1956.Excavation revealed a fortified, gated wooden double stockade, called a “castle,” and 12 long houses, covered with elm bark, inhabited by the Turtle Clan of the Mohawk from 1666-1693.Grassmann’s book "The Mohawk Indians and their Valley