322 



GEOLOGY OF THE SECOND DISTRICT. 



remarkable strata here exposed. It is a pure limestone ; the base is of a dove color, but 

 traversed, or rather reticulated, with scams of calcareous spar. Its beds are very obscure, 

 and it breaks into irregular angular fragments. At Swanton, it is quarried for marble. 



Some other strata prevail here, which arc interesting from their composition, being made 

 up wholly of angular fragments, in which the stratification in each is preserved ; generally 

 they are oblong, or longer than wide, and some of them weigh from twenty-five to one hun- 

 dred pounds. They lie in all directions in the stratum ; for the mass, as a whole, is stratified. 

 Annexed is a cut (fig. 86), representing the manner in which the fragments are arranged. 



Besides exhibiting the manner of arrangement, it shows 

 also the mode in which some of these masses are traversed 

 by veins of calcareous spar. Thus, the dark lines repre- 

 sent those veins which frequently cut through the frag- 

 ments, and they prove very clearly that the cracks were 

 formed in the mass subsequent to the recomposition of the 

 stratum. It is quite difficult to conceive of the mode by 

 which these strata were recomposed, and the whole strati- 

 fied with so much regularity, at the same lime that all the 

 angles of the fragments are preserved as perfectly as they were when first broken ; and it is 

 equally difficult to explain how rocks were, in the first place, comminuted in the way we find 

 them in these strata. 



The Champlam group extends east of Highgate about six miles ; and for this distance, it 

 appears to consist of repetitions of the same masses, which arc occasionally exposed in clitls 

 above the plains, by uplifts, and in many instances by the abrading action of running water in 

 the more depressed portions of this section of country. 



At Sheldon, we leave the Champlain group, and pass directly to the Taconic system ; con- 

 sisting, at its extreme north in Vermont, of the same masses of slate and limestone, as in the 

 counties of Columbia and Dutchess in New-York. 



Taking a general view of the rocks \ipon the east side of Lake Champlain, and those in the 

 same range both north and south, we find them consisting of the upper members of the Cham- 

 plain group. To the east succeeds the Taconic system, whose width is from six to twelve 

 miles, made up of the same members which compose it in Berkshire county, Massachusetts, 

 with the exception of the granular quartz. This general arrangement extends at least to the 

 latitude of Quebec, presenting one of the longest formations yet known to geologists. 



TERTIARY BEDS OF CLINTON. 



Very little information can be gleaned in this county, in relation to the fossiliferous beds of 

 the tertiary. I am able to state only one or two facts. 



The upper beds of the tertiary are wholly wanting : at least they do not appear in place. 

 Upon the lake shore, the clays belong to the lowest part of the mass ; and there being no where, 



