428 Dana — Long Island Sound in the Quaternary Era. 



The course of movement in the valley was S. 10°-15° "W. ; the 

 course outside of it, and that of the upper ice over it, S. 15°- 

 35° E., S. 35° E. being the prevailing course over the higher 

 lands of western Connecticut. 



It was stated also, and proved by glacial scratches, that the 

 south-westing which the ice had in the valley continued for 6 

 to 8 miles west of New Haven, over the Milford 3-egion, 

 and was increased there to S. 34° W. ; and also that Round 

 Hill, west of New Haven, (R, on the map), an isolated hill 304 

 feet high and 110 feet deep in bowlder-clay or till, is situated 

 where the greatest crevasses would probably have been made 

 in the wrenched glacier.* 



If then this change of course, bringing the bottom-ice in the 

 Connecticut valley into line with the upper ice of the glacier 

 took place over the region from New Haven to Milford, a large 

 deposit of drift, S. 20°-35° E. from there, should be looked for 

 in the Sound. This deposit is there. A line from Milford to 

 Mattituck has the course S. 30° E., or that of the general gla- 

 cial movement, so that the Milford-New Haven and Nortkville- 

 Mattituck shore-lines lie in the course of the glacial stream. 

 Now all the way across the Sound between these shore-lines 

 there is shallow water, no soundings exceeding 16 fathoms.. 

 This shallowed region passes oy the east extremity of the south- 

 side channel. The work of deposition was mainly done in the 

 Champlain period, during the melting of the ice, and then, con- 

 sequently, the southern Sound river of the glacier period, had 

 its channel cut off by sand deposits, like so many other streams 

 of the continent. 



This course of glacier movement and deposition is shown 

 -further to have been a fact by the large quantity of red sand- 

 stone — mostly a soft shaly variety — on the shore-hills near 

 North ville, Long Island (north of Riverhead). The surface 

 covered is so extensive that it looked like an outcrop of the 

 Jura-Trias. The facts appear to indicate the position across the 

 Sound of the line of maximum transportation. f 



This south-side channel, if really that of a river carrying 

 fresh water in the Glacial period, required a more elevated con- 

 dition than now of Long Island and the Connecticut coast. 

 Evidence of such an elevation — estimated at 100 to 150 feet — 

 was found in the existence of pot-holes at the sea-level in the 

 gneiss or granite off the Connecticut shore, and in the depth at 

 which clay occurs in the stratified drift in the shore deposits of 

 New Haven Bay. Decisive proof is afforded also by the bays 

 of the north side of Long Island, as suggested by Mr. E. Lewis 



* A map of the Round Hiil region is given on page 358 of the paper, vol. xxvi, 

 1883. 



f On this point see further the paper of this Journal, 1883, xxvi, 355. 



