42 NEW YORK STATE MUSEUM 



Port Leyden it lies at 900 feet above sea level. The distance is 33 

 miles and the difference in elevation 2400 feet which shows a slope 

 of over "^2 feet per mile southward. 



According to Orton/ the Central Square (Oswego co.) well shows 

 Precambric at 2015 feet below sea level, while at Port Leyden its 

 altitude is 900 feet. This shows a drop of 2915 feet in passing 46 

 miles southwestward or a slope of over 63 feet per mile toward the 

 southwest. 



In a deep well at Pulaski the Precambric was struck at 1048 feet 

 below sea level, according to Orton.^ Its altitude at Port Leyden i -: 

 900 feet, which indicates a drop of 1948 feet in a distance of 38 

 miles or a slope of over 51 feet per mile toward the west. 



These results show that the Precambric slope under the Paleozoics 

 is somewhat greater southward than westward and that the general 

 southwestward slope is clearly less than it is in the Little Falls and 

 the Remsen districts. Also the slope under the Paleozoics is greater 

 than where no sedimentaries now cover, which is always true along 

 the southwestern border of the Adirondacks. This is what would 

 be expected because the general surface over the Precambric area 

 has been reduced by erosion since the removal of the sediments. 

 By referring to the above figures we find that if we consider a due 

 east-west line through the Port Leyden district, the Precambric 

 slope under the Paleozoics is actually a little less than it is east of 

 them. This certainly means that the slope of the Precambric sur- 

 face, before the removal of the sediments, must have been steeper 

 eastward from Port Leyden than westward, and that it is still 

 steeper in spite of the later erosion. 



Slope of the Precambric surface during Paleozoic deposition 



It is possible to get some idea regarding the slope of the surface 

 upon which the older Paleozoics were being deposited by comparing 

 the thickness of these formations with the same ones to the west and 

 southwest in Oswego county. This comparison may be most sati:,- 

 factorily made by considering together all of the deposits from the 

 top of the Trenton to the Precambric, because in the well sections 

 the different formations are not clearly distinguished. 



In the well at Pulaski^ the thickness of the strata from the top of 

 the Trenton to the Precambric is 900 feet, while the corresponding 



i/oc. cit. p. 455. 



2 loc. cit. p. 489. 



3 loc. cit. p. 489. 



