Report on the Crystalline Rocks of St. Lawrence County. 



By C. H. Smyth, Jr. 



The field work done in St. Lawrence county during the summer of 1895,, 

 consisted in a continuation of the reconnaissance of the crystalline rocks of 

 the region, begun some time since, and carried on in part privately, and in 

 part under the direction of the State Geologist. This reconnaissance lias now- 

 been extended over about two-thirds of the crystalline area of St. Lawrence 

 county, and also considerable tracts in Jefferson and Lewis counties, the total 

 area covered approximating 2,000 square miles. 



The present report is particularly concerned with results obtained in a 

 new territory comprising the towns of De Peyster, De Kalb, Hermon, 

 Edwards, Canton, Russell, Potsdam, Pierrepont and Parish ville ; together 

 with points re-examined in the towns of Grouverneur, Rossie and Fow ler, 

 which were covered in the examination made during 1893. Certain facts 

 observed during L894, in the towns of Pitcairn, Fine, Clifton, and Diana, 

 Lewis county, which have been already described in part,* may prove of 

 value in this connection. 



In making this reconnaissance, the main object was to learn the distribu- 

 tion of the crystalline limestone formation, for w hich the name Ostvegatchit 

 series w as suggested in a previous report. f A special effort w as also made 

 to ascertain as many facts as possible bearing upon the question of the origin 

 of the great areas of gneisses, and the relation existing between these rocks 

 and the limestones. 



Distribution of Crystalline Li m< j xton< j x. Asa wider territory was covered, 

 the distribution of limestones w as found to conform to the same order as in the 

 case of the more limited areas previously described. Thev form belts, many 

 square miles in extent, stretching in a northeast and southwest direction : 

 and, in addition to these, small scattered patches, irregularly distributed, and 

 varying greatly in size. By far the largest limestone belt is that which is 

 traversed longitudinally by the Rome, Watertown & Ogdensburg railroad 

 From Antwerp to a point some two miles east of I )e Kalb junction. The belt 

 begins at the former village, but extends some miles northeast of the latter. 



* Bulletin Geological Society nf America, VI , pp. -'(i3--JH4. 

 t Report of State Geologist for 1S93, pp. 493-515. 



