130 



CAPE COD GEOLOGY 



1. About a mile north of West Tisbury post office the contact, which 

 is well marked for half a mile, extends northeast and southwest. The fosse lies 

 on the south side of North Tisbury Hill, and it contains several large boulders. 

 (Plate 18, fig. 2). 



2. About a mile southwest of the head of Chappaquonsett Pond there is 

 an ice contact slope and fosse, which at its south end cannot be traced with 

 certainty but which extends to the head of the pond, where it becomes stronger 

 and presents the best example of this feature on the island. The slope is in places 



N 



MORAINE 



ICE CONTACT 



OUTWASH 



Fig. 8. — a. Profile showing relation of bouldery moraine and outwash plain where there is a an ice-contact slope 

 and a fosse. 6. Profile showing relation of bouldery moraine and outwash plain where no ice-contact slope and 

 fosse exist. 



more than 50 feet high and is clearly shown by the contours on the topographic 

 map. This contact is not at the edge of the great plain but was built by the 

 Buzzard's Bay lobe at the edge of a local plain some distance north of the south- 

 ern limit of the Cape Cod Bay lobe. 



3. The most extensive ice contact extends westward from a point about 

 half a mile south of the head of Lagoon Pond. It can be traced for more than 

 two miles, and it curves somewhat to the north as it approaches the state road. 

 It is a typical, clearly marked contact slope, and throughout its course it forms 

 the northern limit of the great plain. The fosse that accompanies it contains 

 in its deepest part a small pond known as Duart's Pond. Unlike the two pre- 

 ceding contacts, this contact was made by the Cape Cod Bay lobe, and it is the 

 only one formed by this lobe on the main island. 



4. On Chappaquiddick there are two short ice contact slopes formed by 

 the Cape Cod Bay lobe. 



