REPORT OF THE DIRECTOR 1<)IJ I2g 



depression in altitude. Today the land area, relieved of this weight, 

 has " sprung " back again. 



Glacial Geology 



During geologic time the climate of the earth has been more 

 uniform than is perhaps realized. Nevertheless slight periodic alter- 

 nations of cooler and warmer periods have occurred and undoubtedly 

 will continue to occur. A lowering of the average temperature by 

 only a few degrees, if long continued, would result in the accumu- 

 lation of vast amounts of ice in the highlands far to the north, and 

 when it acquired sufficient mass, it would have to spread over this 

 and other adjacent regions. This would mark the beginning of a 

 glacial period. 



North America, especially the northern portion, has been subjected 

 to repeated invasions of continental ice bodies. Without much 

 question the Adirondacks have been so invaded many times, but in 

 view of the fact that the glacial deposits are mainly the result of the 

 last ice sheet, we will confine ourselves to it and its results. 



Glacial Erosion 



The great ice sheet crowded its way across the area in a south- 

 westerly direction, grinding off the loose and disintegrated weathered 

 surface of the rocks, widening the valleys and polishing the ledges. 

 On rocky surfaces recently exposed by the removal of the top soil 

 we find today numberless parallel scratches gouged by the scraping 

 or planing action of sharp-edged stones and sand grains frozen in the 

 ice. The direction of these striae informs us of the course taken by 

 the waning stages of the glacier. One set of striae on the east shore 

 of Upper St Regis lake measured south-southwest S 37 W (corrected 

 for true north). Another set of striae was found on a ledge of 

 syenite 3! miles north-northwest of Saranac lake. Here the direction 

 of the ice flow was nearly the same (S 3 8° W). Many striae to the 

 east and south have been noted and recorded; many more will 

 doubtless be found in the Lake Clear district on careful search. 



Glacial Deposits 



The continental ice body picked up and carried with it all sorts 

 of debris which it dropped as it melted. The water, resulting from 

 the melting ice, swept much of this away into .terraces and deltas 

 of lake deposits. Nevertheless a number of well-formed deposits 

 are present in the area; two long, narrow hills southeast of the 



