34 TRANSACTIONS OF THE [nOV. 30, 



Usually the different members of the deposit are separated by- 

 well-marked lines. There are times, however, when the blue shades 

 into the buff and the latter into the stratified sand, this being always 

 the upper member while the blue is the lower. 



At some localities the clay layers are not over an inch thick and 

 alternate with equally thin layers of sand or sandy clay. Such al- 

 ternation is found at Haverstraw, Stony Point, Fishkill, New Wind- 

 sor, Cornwall, Croton, Dutchess Junction, Catskill, and Port Ewen. 

 At all these localities except the last two AVe find the clay covered 

 by or associated with delta deposits, and this interlamination of the 

 clay and sand is probably due to variations in the rapidity of the 

 river entering at those points. 



The delta of Catskill Creek has recently been found at Leeds, 

 some two miles back from the Hudson, and the delta of Rondout 

 Creek will probably be found by following up that stream to the 

 shoreline of the ancient estuary. 



Ice-scratched boulders are often found in the clay, some of them 

 six feet in diameter. 



The thickness of the clay is very variable (see Table I), due to 

 the irregular form of the underlying surface. Sometimes the clay 

 rests on loose till, or hardpan, or, as at Glasco, on the upturned 

 edges of the shales. At Verplank and Montrose the clay lies in 

 basins scooped out of the rock by the glacier. 



From Albany to Catskill the clay is usually underlain by modi- 

 fied drift of a dark gray or black color, and consisting of pebbles of 

 shale and quartz and sand which is mostly comminuted shale. This 

 sand is used for tempering the clay in the manufacture of bricks, 

 but at Catskill contains too much lime for this purpose. The.se 

 underlying masses of sand and gravel are probably kames; the ma- 

 terials composing them show a cross-stratification in many places, 

 they having probably been deposited by the waters rushing from 

 the glacier. At Coeyman's Landing this material is faulted in 

 three places, and at Hudson to the rear of Fitzgerald's yard there 

 are five faults in a space of fifteen feet. 



Borings have been made in the clay at several localities, to wit: 

 At Jover's yard near Roseton a well was sunk 175 feet through 80 

 feet of clay and 95 feet of sand and gravel, and this added to the 

 height of the upper limit of the clay above river-level gives us a 

 total thickness of 180 feet at this point. At Rose's yard to the 

 south of Jover's, a boring was made from river-level 135 feet 

 through blue clay, which added to the 108 feet of clay above river- 

 level gives a total thickness of 243 feet. At Haverstraw the clay 

 is known to extend 100 feet below river-level. 



There is a very interesting clay deposit between Cornwall and 

 Newburgh. The clay layers are in many places wrinkled and in 

 some cases pressed together so as to obliterate the stratification. 

 We also find several terraces of small extent at this locality, to 

 which there are no corresponding ones on the other side of the 

 river ; and finally the clay rests on the glaciated surface of the rock.- 



