HEROD GKAVELS 381 



the Wisconsin. For these reasons it seems probable that the clayey 

 sands are to be referred to the Jacob formation. 



Along the base of the bluff on the south side of the high hill south of 

 West harbor a thickness of 10 feet of pinkish and brown sandy clay alter- 

 nating with lamina? of sand is exposed in a low anticline about 100 feet 

 across and a few feet high. This is overlain by gravels of the Herod type 

 and belongs without doubt to the Jacob sands. 



Herod gravels — Use of term. — The term " Herod gravels " is applied to 

 the gravels, often from 30 to 50 feet and perhaps in places 100 feet in thick 

 ness, which rest conformably upon the Jacob sands and are overlain by 

 the Montauk drift, the contact of which is normally conformable, but 

 which may be replaced by an unconformity due to contemporaneous 

 erosion. It is developed throughout Long island and eastward to Block 

 island, but is generally cut out by the unconformity farther east. The 

 name is from Herod point, near Wading River, on the north shore of Long 

 island, at which locality the gravel is well exposed. 



Conditions of deposition. — The conditions as regards submergence 

 which existed during the Jacob deposition continued without very ma- 

 terial change through the period of deposition of the Herod gravel. 

 The change from the fine sandy Jacob silts to the latter gravels indicates 

 a near approach of the ice which furnished the materials and the inaugu- 

 ration of swifter currents as indicated by the coarseness of the material 

 deposited. In fact, no clay or fine silts could have been deposited if cur- 

 rents of like strength had existed during the period of Gardiner or Jacob 

 deposition. Whether this was due to currents resulting from the drain- 

 age from the ice, from the differences in the depth of water, or from 

 changes in the tidal or other currents resulting from the position of the 

 ice-front can not be established with the information now available. It is 

 believed that the deposition took place under the sea at a distance of only 

 a few miles from the ice-front. The water was deep enough to float bergs, 

 as is indicated by an occasional berg-dropped boulder or by boulder 

 pockets supposed to have been formed through the grounding and melt- 

 ing of bergs. The limited distribution of the boulders of the pockets 

 would seem to show that the bergs were of no great size, indicating that 

 the water was probably shallow at the time. That the ice-margin was 

 close at hand, at least in the later stages, is to be inferred from the fact 

 that the gravels merge upward into semi-till, which could only have 

 been formed in the near vicinity of the ice. 



Character of gravels. — The Herod gravels are predominantly sandy, 

 but with a good proportion of pebbles, mainly of granitic rocks. The 

 granites are somewhat weathered, but on the whole do not differ mark- 

 edly from either the older or younger glacial gravels of the same type. 



