PLEISTOCENE MARINE SUBMERGENCE 3I 



drainage, in the marine estuary, but the prevaihng steep walls of 

 the valley, with absence of heavy tributary drainage, has prevented 

 the construction and preservation of conspicuous deltas. Of course, 

 cliff-cutting and bar construction were negligible in such narrow 

 w^aters. 



But northwest of Ossining is one of the best deltas in the valley, 

 and the finest in the present water. Croton Point, projecting 2 

 miles into the Hudson river, is the remnant of the heavy delta of 

 Croton river. It is incontrovertible proof of high-level water in 

 the Hudson valley since the glacier vacated. Some small remnants 

 of the great delta are found in the level patches north of Ossining, 

 but the greater part of the original delta has been cut away bj' 

 the same stream that built it, aided by the tides and waves of 

 Tappan Sea. The delta promontory represents the north flank of 

 the original filling, and an evidence of the erosion is seen in the 

 gap across the middle of the promontory. 



The broad sand plain at the head of the promontory is definitely 

 100 feet altitude, by the topographic map; but this does not give 

 the full height of the Hudson estuary. An examination of the 

 ground in company with Professor Berkey finds that the summit 

 water level is at about 120 feet. The 100- feet plain was under- 

 v^^ater, though wave-swept by the lowering (relative to the land) 

 waters. Merrill made the usual mistake of taking the highest 

 broad and conspicuous plain as marking the water surface. In 

 some cases this may be the fact, but commonly not so. 



On the west side of Haverstraw bay, at Haverstraw, West 

 Haverstraw (Bensons Corners), and North Haverstraw, are thick 

 clays and capping sands lying in an embayment of the broad valley. 

 The summit altitudes of the sand plans agree closely with the 

 profile in plate lo. 



The northern portion of the low ground west of the Palisades, 

 mentioned in the preceding chapter, is shown on this sheet. 



West Point sheet. North of Verplanck the clay pits of an aban- 

 doned brick factory testify to the deep water of the Hudson 

 estuary', and the capping sands are seen a mile northeast of the 

 village. Here leveled sands and weak bars indicate the full height 

 of the waters, about 125 feet. 



Southwest of Peekskill for 2 miles the careful observer may see 

 ihdeterminate inscriptions of the high waters. The state camp, 

 over a mile northwest of Peekskill, is on a delta terrace with an 

 altitude of 105 feet, some 25 feet inferior to the summit level. 



Across the river from Peekskill is one of the most interesting 



