228 TS. Hunt on some points in the Geology of Vermont, 
localities. Thus at Brookville, Mr. Billings found Levis fissik 
immediately above and below the white marbles, clearly showin 
these beds of white crystalline limestone to belong to 
portion of the Quebec group. This confirms the view exp 
by me in this Journal for May, 1861, page 392, that these: 
bles represent a great development of calcareous matter in 
Quebec group and are to be regarded as beds of chemically 
cipitated carbonate of lime, and not limestones of organic 
gin. Their great purity and crystalline texture dependt 
original conditions of deposition, and not upon any subs 
alteration. : | 
In this connection it may not be out of place to notices 
of the views of the late Dr. Emmons which have lately been 
referred to this Journal, II, xxxii, 427, and xxxiil, 3 
According to Mr. Perry, the slaty rocks which appear é 
east and west of the Red Sandrock, belong to two , 
conic. In the latter he includes the Georgia slate wit 
mordial species and the Swanton slate considered 10! 
: ? c, ane 
glomerates of the Quebec group. This Middle Taconic 
up of three distinct series of black and brown 
however, older than the Potsdam : eee 
Ast. His Swanton slates. These are the Utica an OE 
River formations which are distinctly overlapped by ™ 
dam at varicus points along its western border, 78 
shins and ei Point, near Burlington, where 
postion is clearly seen, and where Triarthrus © 
is found in the underlying Hudson River slates. i 
section, showing the superposition of the Potsdam 
aoe an hemp at St. Albans, : given by Mr. } 
in the Geology of Vermont, page 37: egy 
2d. The le slates wich ate but an inter’ 
i of the Potsdam, as appears from the section at sas 
