330 



EED SANDKOCK. 



Burlington, and Penniman's lime kiln, in Colchester. It was originally drawn very 

 carefully by Prof. Thompson. 



The different varieties are specified in the explanations below the figure. But upon a 

 part of this section the red sandrock series is concealed by alluvium. Therefore we 

 introduce Figs. 237 and 238 to show what rocks crop out at Burlington, along the line 



FIG, 237. 



Section from the lake, through Willard's Ledge to Spear Street. 



of the strike of those rocks that would be found in the marshy and alluvial interval 

 of the preceding sketch, if it be extended. The ledges are mostly varieties of red sand- 

 stone. Fig. 238 shows what the particular layers are at Willard's quarry, a is jointed 

 red sandrock ; 6 is a contorted stratum of the same, seven inches thick at the northeast 

 opening of the quarry, and was about twelve feet below the top of the quarry in 1847. 

 c is variegated sandstone ; d is a slaty rock with a green surface. The other layers are 

 the ordinary flagging stone derived from this formation. The section ending at Spear 

 Street, joins No. 7, in Fig. 236, after a short interval. 



FIG. 238. 



FIG. 239. 



Willard's Ledge, N.E. opening 



Quartz Ledge below the High Bridge. 



Fig. 239 represents an enlargement of No. 9, in Fig. 235, east of Winooski Falls, in 

 Colchester. The bluff rises very abruptly from the eastern margin of the first terrace, 

 above Winooski Lower Falls. The first precipice of about twenty feet, is nearly perpen- 

 dicular. Two or three feet at the base (37), are silicious limerock. The rest of the 

 perpendicular wall (36), is nearly white quartz, formerly used for the manufacture of 

 glass in Burlington. For a rod or more east of the summit of this precipice, the rocks are 

 covered by soil, the ground gradually rising to No. 35, which is composed of brown quartz. 

 No. 34 is slaty sandrock very evenly stratified. No. 33 is quartz rock, overlaid by cal- 

 ciferous sandrock, massive, and without any marks of stratification. The whole thickness 

 of this ledge of quartz is fifty feet. 



