178 



CAPE COD GEOLOGY 



Subdivisions 

 The Manhasset formation is divided into three members — a lower bed, 

 known as the Herod gravel, a middle bed, known as the Montauk till, and an 

 upper bed, known as the Hempstead gravel. The upper and lower members 

 are beds of similar glacial sand and gravel, and where the till bed is not present 

 it is impossible to distinguish the Herod from the Hempstead. The Montauk 

 till is easily recognized both by its position and its nature, the Wisconsin till 

 being usually quite different, unless it lies directly on the Montauk till or has 

 been formed of reworked Montauk material. These subdivisions of the Man- 

 hasset are the same as those on Long Island, and they are of essentially the 

 same nature. 



General Distribution 

 The Manhasset formation is best seen along the shore of the western area 

 and in Squibnocket, Stonewall Beach, and Nashaquitsa cliffs. It probably exists 

 all along the shore of the western area and extends well up on the older core of 

 the morainal highland. It also occurs in the northeastern area, but there it is 

 not so well displayed and probably only its upper members are ever exposed. 

 It doubtless underlies all the moraines of this area, although a large part of it 

 is below sea level. Under the great plain the Manhasset no doubt underlies the 

 out wash gravel, although it has not been clearly seen. Even if its upper member 

 were exposed in this area it would probably be indistinguishable from the out- 

 wash gravel. From the great plain the Manhasset extends well up the southeast 

 side of the core of the morainal highland in the western area. 



Herod Gravel Member 



Name. — "The name Herod gravel member is applied to the sand and 

 gravel beds constituting the lower member of the Manhasset formation, or that 

 part lying below the middle or Montauk till member. The name is taken from 

 Herod Point, near Wading River, on the north shore of Long Island, where 

 the gravel is well exposed." 1 The position and nature of these beds being exactly 

 the same on Marthas Vineyard as on Long Island, the same name is here used 

 for them. 



Character. — On Marthas Vineyard the Herod gravel varies from a fine 

 gravel to a sand. The change from gravel to sand in the vertical succession 

 takes place abruptly, but the beds do not everywhere hold their character for 



duller, op. cit., p. 121. 



