32 NEW YORK STATE MUSEUM 



sand plains, unfortunately now mostly removed. Jones point has 

 been for many years one of the sources of sharp sajid and gravel 

 used in New York City construction. Seen from across the river, 

 or from the steamers, it yet shows the line of the gravel terrace 

 banked against the Dunderberg mountain. The map is faulty 

 and does not indicate even the remnant of the original plain. The 

 north end and highest part of the plain is at about 130 feet above 

 the sea. The southward slope of the summit shows clearly when 

 seen from some distance. The structure and location of the gravel 

 terrace, in relation to the mountain and valley, prove that it was a 

 glacial delta. Its position rules out any possible land drainage. It 

 was built by a glacial ice-border stream which flowed along the west 

 edge of the ice lobe and which received the contribution of the 

 land drainage north of the Dunderberg. The lower portion of the 

 deposit is very coarse, containing thousands of boulders. The top 

 and the southern end are finer, with the foreset and topset beds 

 well displayed. 



The geographical relations of the Jones point gravel terrace rule 

 out, as explanation of the receiving water, any suggestion of glacial 

 ponding alongside the ice lobe. The waters were the open Hudson 

 inlet or estuary. 



The constricted valley between Peekskill and West Point could 

 not hold any large shore features; but minor features can be seen 

 from the opposite side of the valley, or from the river steamers, 

 and such have been measured at Fort Montgomery and Highland 

 Falls. 



At West Point the parade ground is the theoretic height for the 

 summit level of the estuary, about 150 feet. But there has been 

 so much grading and interference with the natural surface that 

 precision in this locality is not attempted. 



The terraces a mile northwest of West Point and across the 

 river east of Cold Spring are contoured at 160 feet. As these lie 

 in embayments of the valley walls they probably were marginal to 

 the shrinking ice lobe, as described by Woodworth (82, pages 

 111-13), and were graded somewhat above the open waters to the 

 south. The control of the waters on the West Point side must 

 be the steep slope south of the point; on the Cold Spring side the 

 channels of outflow control will probably be found opposite the 

 point, a mile northeast of Garrison. 



West Point, Schunnemunk and Newhurg sheets. At the junction 

 of these three quadrangles with the Poughkeepsie quadrangle two 

 large and interesting deltas are found, one affording the site for 

 the city of Beacon and the other for part of the city of Newburgh. 



