882 M. L. FULLER — GEOLOGY OF FISHERS ISLAND 



In fact, the Herod gravel must usually be identified by its stratigraphic 

 position between the Montauk drift and Jacob sands. 



Details of occurrence. — The Herod gravels are best exposed ii: the 

 clay pit, where the sandy phase is strongly developed in the big anti- 

 cline bringing up the Gardiner clay and Jacob sands. The relations and 

 structure at this point are well shown in figure 6. Figure 11 shows ad- 

 ditional details of the structure, although, owing to the talus present, 

 the relations are not entirely revealed. 



At Isabella beach the Herod gravels are seen resting on the Jacob 

 sands and with them are arched up in broad open folds (figure 7). The 

 conditions at the West Harbor locality (figure 10), except that the mate- 

 rials are there moderately coarse gravels with pebbles the size of an egg, 

 are similar to those at Isabella beach. The greater part of the high hill 

 on the south shore south of West harbor appears to be composed of 

 Herod gravels, which seem to be cross-bedded on an extensive scale, and 

 which are, judging from the outcrop of the Jacob sands on which they 

 rest, folded into broad arches of a few feet in height. 



53 s 



Figure 11.— East-west Section in Clay Pit. 

 Showing details of folding in the sandy phase of the Herod gravels ; clay at base. 



Except at the localities described, where the gravels are seen resting 

 on the Jacob sands, the Herod beds can not be recognized with absolute 

 certainty, although there is every reason to believe that the yellow and 

 buff sands and gravels, which are seen at a great number of points be- 

 neath the thin coating of Wisconsin till, belong to this formation, form- 

 ing, in fact, by far the greater part of the island. They probably reach 

 their greatest development either in the high hills south of West harbor, 

 already mentioned, or in the similar hill southeast of Chocomount cove, 

 which rises to over 120 feet above sealevel and is probably composed 

 mainly of Herod gravels. 



Montauk drift — Use of term. — The designation " Montauk drift " is ap- 

 plied to a sheet of drift from 20 to 50 feet or more in thickness, which nor- 

 mally overlies conformably the Herod gravels. Owing to the fact that it 

 was laid down in more or less direct connection with an ice-sheet which 

 alternately eroded and deposited, local unconformities, due to contempo- 

 raneous erosion and sometimes cutting as deep as the Gardiner clay, are 

 not uncommon. The material is ordinarily partly stratified, but retains 

 a distinct till-like appearance, owing to the big, probably berg-dropped, 



