Wright.] 430 [Dec. 21, 



course at the rate of two or three feet a mile, and is narrow. But 

 at Trenton it suddenly enlarges, and comes down to the level of 

 the tide. Here a wide and extensive delta-terrace is deposited, 

 being about three miles in diameter. The surface of this delta- 

 deposit is about fifty feet above tide and has a clearly defined mar- 

 gin all around, being composed of material derived from the valley 

 above, and such as characterizes the glacial terraces lining the 

 valley up to and beyond the terminal moraine ; in short, it is a 

 deposit of the overwash gravels laid down during the periodical 

 floods incident to the presence of glacial ice in the upper portions 

 of the drainage basin of the river. 



Since my first visit to Trenton I have studied attentively all the 

 streams situated like the Delaware with reference to the glaciated 

 area between the Atlantic Ocean and the Mississippi River, and can 

 state from personal observation, as partially recorded in the pub- 

 lications referred to, that a common cause, which cannot be any- 

 thing else than glacial floods operating while the ice remained over 

 the headwaters of these streams, has been at work making gravel 

 deposits similar to those described along the Delaware. The ac- 

 companying cuts (see Figs. 2 and 3) show the relation of the various 

 streams in Pennsylvania and Ohio to the continental ice-sheet 

 while its front continued on the southern watershed of the conti- 

 nent. Without exception, those southerly flowing streams, whose 

 drainage area lies to any considerable extent within the glaciated 

 regions, are lined by extensive terraces of the overwash gravel of 

 the glacial period. 



On obtaining definite information as to these facts, I at once 

 pointed out in my article in the American Journal of Science, vol. 

 xxvi, pp. 7-14, as well as in my report to the Western Reserve 

 Historical Society, pp. 26-27, and in the Ohio Archaeological and 

 Historical Quarterly, vol. i, pp. 176-177, the importance of having 

 local observers turn their attention to the discovery of palaeoliths 

 at varions points in Ohio, where the glacial conditions were similar 

 to those in the valley of the Delaware at Trenton, N. J. The lan- 

 guage in m} T report to the Western Historical Society (p. 26) is as 

 follows : "The gravel in which they [Dr. Abbott's implements] are 

 found is glacial gravel deposited upon the banks of the Delaware 

 when, during the last stages of the glacial period, the river was 

 swollen with vast floods of water from the melting ice. Man was 

 on this continent at that period when the climate and ice of Green- 



