VARIETIES. 



329 



that this belt of limestone runs through the whole of Hinesburgh and Monkton, connecting 

 together the two great deposits of the Eolian limestone. Other beds probably run through 

 and may belong to the same belt, but repeated upon the numerous folds. The limestone 

 of this formation, between Burlington and Highgate, is embraced under the fifth variety, 

 dolomitic. For the analysis of the Winooski marble gives 



Silica, . . . 10.304 



Alumina and iron, . 12.251 



Carbonate of lime, . 35.310 



Carbonate of magnesia, 42.235 



100.100 



The magnesia is in excess, and the silica is combined with the alumina and iron, there 

 being less than two per cent, of iron present. It is surprising that this complicated rock 

 should be decomposed with so great difficulty. The colors of this dolomite vary from 

 bright red through chocolate, brown, and greenish brown, to grayish white. It is usually 

 mottled, and sometimes brecciated, when it is penetrated by white veins of calcite. We 

 have called this variety the Winooski marble ; not to multiply local designations, but to 

 designate a peculiar variety of the red sandrock series, using the name by which it is 

 known in economic geology. To gain a proper idea of the different varieties of the 

 Winooski marble, we refer to the detailed accounts of Sections IX, X, XI, XII and XIII, 

 where the varieties are described in a descending order. 



The greenish shale and novaculite schists are very much alike. The former are inter- 

 stratified with strata of sandstone in the northern part of the terrain, particularly at 

 Charlotte, where cleavage planes are abundant in them. The latter form masses of rock 

 by themselves in the east part of Swanton, and the north part of Franklin. They pass 

 into clay slate. These seams of clay slate are of sufficient extent to deserve notice as a 

 distinct variety. 



The rock that we call talcose schist or talcose grit, in Vermont, is found in this group. 

 As shown elsewhere there is generally very little magnesia present. Specimens of this 

 green schist are found in the southeast part of Burlington. 



Having specified the characters of the principal varieties of the rocks composing the 

 red sandrock series, we proceed now to give a few local sections to show the relative 

 position of these varieties to one another. We select from a large number of drawings 

 on hand. Fig. 236 represents the character of the rocks between Appletree Point in 



Fio. 236. 





3456 7 8 9 



Section in Red Sandrock from Appletree Point to Penniman's Lime Kiln. 



H 



1 Utica slate. 



2 Hudson River slate. 



3 Winooski limestone. 



10 Silicious limerock. 



11 Eolian limestone. 



4 Marshy ground. 7 Red sandrock. 



5 Intervale. 8 Silicious limerock. 



6 Winooski River. 9 Stratified quartz. 



Phaca Ledge refers to the fact that at this point there is an excellent locality of rare plants, conspicuous among which 

 is the Phaca Rollimii (Oakes.) 



22 



