GEOLOGY AND GEOGRAPHY OF CLAY DEPOSITS 111 



Along the river behind the yards of the Excelsior and Diamond 

 Brick Co. most of the overlying material has been removed by 

 stripping, but judging from what is left it must have been 10 to 

 15 feet thick. South of Haverstraw the contact of the clay with 

 the underlying drift can be observed, the clay thinning oat as it 

 approaches the hill. Some two miles south from Haverstraw, 

 and half way between the stations of Ivy Leaf and Thiells on 

 the New York & New Jersey E.. R. in the valley of Ivory 

 Creek, is a basin-shaped deposit of clay belonging to E. W. 

 Christie. It is not over 15 feet thick as determined by boring, 

 and has a slightly elliptical outline. The valley in which it lies 

 is full of glacial material, and contains numerous kames, whose 

 axes lie parallel to the direction of the valley. The clay is under- 

 lain by drift material containing bowlders of quartzite, calcifer- 

 ous sandrock, granite, sandstone, gneiss and schist. Over the clay 

 is one to two feet of sand containing large ice-scratched stones of 

 quartzite, gneiss and schist. This clay deposit was probably 

 formed in a small lake. If it were a portion of the Hudson 

 River estuary deposits, it would indicate a much greater sub- 

 mergence than that of 100 feet, supposed for this region, 

 for this localit}^ is 250 feet above the level of the Hudson River. 

 On either side of the track at Thiells are probably remnants of a 

 terrace. 



The clay bank of the Anchor Brick Co. at Croton Land- 

 ing, is elliptical in outline and lies on a bed of granite, gneiss, 

 schist, and white crystalline limestone pebbles, cemented together 

 by clay, covered with limonite. Large pebbles are scattered 

 through the clay, the layers of which are undulating, conform- 

 ing to the shape of the underlying surface. Over the clay is 

 four or five feet of gravel and sand. South of this yard an exca- 

 vation has been made under the terrace for obtaining gravel, 

 exposing a section of Croton delta. Projecting up into it is a 

 mass of bowlder- till. 



About the middle of Croton Point are the clay-pits of the 

 Underbill Brick Co. Their clay is overlain by the sandy 

 beds of Croton delta. The material composing it was evidently 

 derived from the crystalline rocks of the surrounding country. 

 It is often micaceous and of a 3''ellow color. Scattered through 

 this sand are great numbers of botryoidal sand concretions, some 



