EIvISHA MITCHEI.L SCIENTIFIC SOCIETY. 58 



"(6)Pebbly and semi-brecciated quartz. 



"(7) Common brown quartz. 



This rock ^ ^ - ^ is associated with " '• " tal- 

 cose slates. It is repeated two or three times. "' '" ^ 

 It frequently contains beds of pebbles. But its most in- 

 teresting- feature appears in its passag-e into hornstone, 

 chert or flint." 



The apparent vitrification he considers due to a chem- 

 ical combination of the particles, that is, to a cause inde- 

 pendent and distinct from heat. 



"Ag-almatolite" (pyrophyllite) is mentioned as occur- 

 ring' in beds in this Lower Taconic series. And lime- 

 stone, containing' talc and tremolite, is said to be associated 

 with slate and quartz, 



Emmons' rocks of the Lower Taconic, then are:^ 



(1) "Beds of talcose slates. (2)Qu:irtz n)cks with their 

 alternating" series of talcose sla;es. (3) Beds of ag'alma- 

 tolite. (4) Limestone with its interlaniinated slates. 



The Upper Taconic. "This division of the system is 

 not very clearly marked. ^ " " In North Carolina 

 the lineof demarcation is sometimes difficult to define. But 

 the rocks which I reg-ard at the present time are (in as- 

 cending* order)'^: 



(1) "Arg-illaceous, or clay slates, with many subordi- 

 nate beds, roofing- slates, mountain slate. 



(2) "Chloritic and arg-illaceous sandstones, flag-g-ing- 

 stones, etc. . 



(3) "Brecciated cong-lomerates. 



The ordinary solt, g-reenish slates may be re<>-arded as 

 the prevailing- mass of the first division. The predominant 

 color is g-reenish g"ray. A red decomposed variety is 

 mentioned as being- common near Pittsboro, Chatham 

 county. "The subordinate beds are fine siliceous ones 

 passing- into chert or hornstone. * * ■'■ " The colors 

 are blue, purple and g-reen." 



1 Ibid, p. 55. 



2 Ibid p. 65. 



