GEOLOGY OF THE PORT LEYDEN QUADRANGLE 35 



1280 feet above sea level. Thus in a distance of 25 miles the top 

 of the Trenton drops 1485 feet or shows a southerly dip of nearly 

 60 feet per mile. 



According to Orton/ the top of the Trenton in the Central 

 Square (Oswego co.) well was struck at 1209 feet below sea level. 

 The same horizon 2 miles west of Port Leyden is at an altitude of 

 1280 feet above the sea which thus shows an increased elevation of 

 2489 feet within 44 miles or a southwesterly dip of over 56 feet per 

 mile. 



In the Stillwater (Oswego co.) well Orton ^ reports the surface 

 of the Trenton at 25 feet below sea level and this is 1305 feet below 

 the same horizon 2 miles west of Port Leyden. The distance is 

 30 miles and the westward dip is over 43 feet per mile. 



Within the map limits, near Locust Grove, the Trenton-Utica con- 

 tact is at an elevation of nearly 1300 feet, while 2 miles to the 

 southwest it is a little over iioo feet, thus indicating a southwest- 

 ward dip here of about 50 feet per mile. 



An exceptional dip of 3 or 4 degrees toward the southvv^est may 

 be seen in the Trenton limestone in the vicinity of Martinsburg. 

 This is probably due to the updrag effect of the fault below 

 described. 



Faults and folds 



No fault of sufficient extent to be mapped has been found within 

 the limits of the quadrangle. A few places have been noted where 

 there have been slight movements of i or 2 feet as for example in 

 the Trenton of the Black river gorge 2^ miles northeast of 

 Boonville. 



Just beyond the edge of the map and in a ravine ^ of a nule 

 northwest of East Martinsburg station a fault with considerable 

 displacement is w^ell shown. No detailed study of this fault has 

 been made, but it is of the normal type and strikes approximately 

 northwest-southeast. Its length was not determined. The fault 

 plane stands nearly vertical and the limestone 'beds are highly in- 

 clined on the south side as a result of the updrag during the process 

 of faulting. On the north side of the ravine the Precambric lies 

 fully 40 or 50 feet higher than on the south side and this represents 

 the amount of the throw. The Pamelia beds have been faulted 

 against the Precambric. The unusually rapid downward slope of 



1 N. Y. State Miis. Bill. 30. 1899. p. 455. 

 - he. cit. p. 448. 



