72 MEETING, MONDAY, APRIL 3. 



a northwesterly course through Columbia county, rising 

 to the summit of the Alleghanies in Lycoming county, 

 and crossing them diagonally through Tioga and Potter 

 counties, where the general elevation of the country is 

 ujDwards of 2,000 feet. From Potter county the mo- 

 raine enters Cattaraugus county, N. Y., and continues to 

 trend northward as far as Little Valley, six miles north 

 of Salamanca, where it makes a sharp turn to the south- 

 west, running nearly parallel with the Alleghany river to 

 Columbiana county, Ohio. The whole length of the line 

 explored this last summer is about four hundred miles. 

 The signs of glacial action abruptly cease along this line, 

 and it is marked by a special accumulation of unstratified 

 material composed of clay, scratched stones, and granite 

 boulders. North of that line the signs of glaciation are 

 everywhere apparent. South of it there are no scratched 

 stones, no transported boulders, and no " till," or boulder 

 clay. Where streams cut through the line, however, 

 boulders of granite and quartzite have been transported 

 by water and deposited in terraces and deltas. The gravel 

 of Trenton, N. J., in wdiich Dr. C. C. Abbott has found 

 palaeolithic implements is in a delta terrace thus formed 

 when the river was fifty feet higher than now. Every 

 stream to the westward, w^hich rises in the glaciated region 

 and flows through the unglaciated region, has formed 

 corresponding terraces and deltas, and is full of interest. 

 Thorough search for palaeolithic implements should be 

 made in all such formations. 



The majestic proportions of the great ice movement 

 are seen in the fact that it advanced as far south upon the 

 mountains as in the valleys. For example, the valley 

 between the Kittatinny and Pocono mountains, though 

 twenty miles wide and one thousand feet deep, caused 



