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GEOLOGY OF THE SECOND DISTRICT. 
St. Lawrence county, though so well watered by living streams, has few lakes, in conse 
quence of not extending as far east as the table land upon which they are so numerous. 
Black lake is the largest and most important; it is twenty miles long ; and as Indian river 
empties into it, it may be made a medium of travel or navigation still farther. Its shores are 
low, and so far as scenery is concerned, it is not likely to be celebrated or praised. 
The Great Geological Divisions of St. Lawrence. 
For all useful purposes, and also for accuracy, it will only be necessary to divide this county 
into three principal regions : 1, The Primary region, comprehending hypersthene rock, gra¬ 
nite, gneiss and primary limestone ; 2, Sandstone region; and 3, Limestone region. The 
particular kind of sandstone and limestone will be stated in the proper place. 
The first region or division comprehends more than one-half, but less than two-thirds, of 
the county. In general, I may say that all that part east of Canton is primary. But to be 
more precise in these boundaries, as they are few, and may be given with some degree of 
exactitude, I will commence at the extreme south, and proceed northeast. The primary extends 
over to the west side of Black lake, but only upon an average seventy or eighty rods, form¬ 
ing a narrow belt upon that side of the lake. It crosses two miles north of Depeyster, and 
runs nearly through the centre of the town towards Canton, running east two or three miles 
of the natural canal. From Canton, the line of junction between the primary and transition 
pursues an undulating course, running three or four miles east of Potsdam ; the primary, 
however, appears at the village, thence to Parishville, and onward to Hopkinton. The line 
of junction, though it is described as pursuing generally a direct course, still it is more or 
less undulating the whole distance, varying on either side two or three miles. The course I 
have given, therefore, is what it purports to be; the general direction being sufficiently accu¬ 
rate and correct for all useful purposes. 
I have now given the boundary line between the primary and potsdam sandstone. What 
remains is to make a similar line of demarkation between the latter and the limestone region, 
or that which is underlaid by the calciferous sandrock of Eaton. 
Commencing as before at the extreme southern portion of the county, a few miles south of 
Morristown, the line runs nearly parallel with the St. Lawrence river, crossing the Oswe- 
gatchie four miles east of Ogdensburgh; it then diverges to the east, and adheres to that 
direction until it crosses the De Grasse river two miles east of Columbia, when it runs again 
about parallel with the St. Lawrence to Norfolk, whence it still pursues nearly the same 
direction to Brasher and Hogansburgh in Franklin county. 
These lines of demarkation divide the county into three great regions in which the physical 
geography differs, and also into three distinct geological formations. They are unequal as to 
size, as has been remarked, but still we may consider the county as divided into three zones 
or belts ; the eastern, central, and western. All of the first is entirely primary; all of the 
central, potsdam sandstone ; and all of the western, which lies along the St. Lawrence, is 
composed of the calciferous sandrock of Eaton. 
