GLACIAL AND POST-GLACIAL HISTORY 433 



forms to which the steep edges of the plateau descend. The indica- 

 tions from the surface and from well data are that it is composed of 

 gravel and sand. A well on the top of the plateau near the west side 

 at the house of Mr. Neely is reported to have penetrated 120 feet of 

 gravel and sand from an elevation of 100 feet A. T. without reaching 

 rock. 



The kame-Kke gravel knoll at the northeast edge of the plateau is 

 situated south of the North Haverstraw Station of the West Shore 

 Railroad. An exposure shows about 20 feet of coarse gravel. Far- 

 ther south, east of the railroad, where the gravel likewise has a 

 kame-like form, the layers dip north and south and east. North of 

 these kames toward Stony Point clay occurs up to 40-60 feet, and 

 has a form which may be due to erosion. 



Low-level gravel, and clay. What appear to be low-level terraces 

 derived from the erosion of the higher gravels have been observed in 

 the form of discontinuous shoulders on the north side of the Haverstraw 

 gravel plateau on the slope to Cedar Pond Brook at elevations of 60 and 

 40 feet. A 40-foot level on the southeast side of the North Haver- 

 straw plateau, and also a 60-foot level southwest from the 40-foot 

 level, may represent a product later in origin than the plateau itself. 

 It may be said, however, that where the level of stratified drift varies 

 so greatly as it does in this region it is not easy to determine posi- 

 tively that the shoulders of limited area and uncertain relations are 

 of later origin than the higher gravels, and do not represent remnants 

 of undulations descending to the lower levels made while the ice was 

 present. A wide plain extending along the water front from near Short 

 Clove to Grassy Point, with an elevation by the topographic map 

 of less than 20 feet A. T., has been so worked over in the making of 

 bricks that it is difficult to say what was its original height and extent. 

 Some exposures have been observed in it in which the materials 

 included rounded pebbles of clay, evidently derived from the erosion 

 of the higher level clays. In exposures near at hand and at about the 

 same level the layers have a southerly dip at a high angle, thus sug- 

 gesting lower-level delta deposits made from the erosion of the higher 

 gravels and clay. At Grassy Point (south of No. 17, Fig. 9) there are 

 deposits in this lowland which were made in the presence of the ice. 



No exposures which reveal the structure occur in the 60-foot and 



