274 



CAPE COD GEOLOGY 



showing signs of erosion by running water subsequent to the melting of the ice 

 sheet in the fosse. Manomet River, which drained the glacial lakelets in the 

 interlobate moraine, enters the fosse at North Sandwich and has cut a channel 

 below the old glacial level of the stratified drift, forming a low terrace. At the 

 west end of the fosse, on the shore of Buzzards Bay, the mouth of the river 

 is bordered by sand flats that appear to have been formed in glacial time. We 

 may therefore suppose that water once discharged from the basin behind the 

 Falmouth moraine across the divide in the fosse to lower ground in the depression 

 occupied by Buzzards Bay. 



The height of the water level up to which the Eastham plain was constructed, 

 in Grabau's view of its origin, is not readily determined. The eastern cut edge 

 of the plain at the grass line on the cliff obviously does not indicate the water 

 level on either the old view that such plains were formed entirely under standing 

 water or on the modern view that outwash plains of this kind are formed above 

 the level of standing water. According to the old view, as the plain originally 

 extended farther east and rose in elevation in that direction, the water level 

 would have to be put at an indefinite height. The summit of the cliff stands 

 somewhat below 80 feet. The North Eastham railroad station, which stands 

 about midway across the southern part of the plain, in the upper part of the 

 stream creases, stands at an elevation of 69 feet. In the areas west and north- 

 west of this station the western edge of the plain proper accords roughly with 

 a water level between 20 and 40 feet, but at some places, as west of the Methodist 

 Camp Ground and on the coast near Fresh Brook, where the plain is now narrow- 

 est, its western edge bears knobs of drift that have steep ice-contact faces on the 

 west, showing that they were formed in the presence of masses of ice. The 

 plain may have been built up by streams that discharged water into the site 

 of the Bay at a height about 30 feet above the present sea level, but the stream 

 creases descend to and below the present sea level in the area around Fresh Brook. 

 These stream creases were formed when the load of sediment had fallen off and 

 the water discharged from the ice was cutting down the plain to a lower base 

 level than that at which it was constructed. The streams at this stage could 

 not have discharged through the Manomet fosse into the Buzzards Bay region 

 but must have found some point of escape out of the bay at a lower divide in 

 the morainal barrier on the south, for the deep channel of Pamet River and the 

 now open bay on the north were then probably closed by the ice sheet. The 

 only passage sufficiently low to conform in height to these creases is that from 

 Boat Meadow Creek through Jeremiah's Ditch into Town Cove, in Orleans, in 



