ABSTRACTS AND DISCUSSIONS OF PAPERS 63 



represent an outcrop of the Upper Banff shale in its normal position with 

 respect to the underlying Rocky Mountain quartzite. 



The finding of the Albertella fauna in place is not the least interesting of 

 Professor Adams' results. The reference of this elusive drift-block fauna to 

 the Middle Cambrian instead of the Lower Cambrian has been confirmed dur- 

 ing the past summer by its discovery in place in the type section on Mount 

 Bosworth, British Columbia, some 700 feet above the base of the Cathedral 

 limestone. The definite placement of this fauna is of value in connection with 

 the discussion of the Precambrian age of the rocks of the Galton and Purcell 

 series, since the latter are now known to be older than the Albertella fauna. 

 That they are still older is evidenced by Dawson's early and hitherto un- 

 recorded discovery of Lower Cambrian fossils in the Kootenay Valley south 

 of Upper Columbia Lake. 



Brief remarks were made by Prof. Alfred C. Lane, with reply by the 

 author. 



EMERALD DEPOSITS OF MUZO, COLOMBIA 

 BY JOSEPH E. POGTJE 



(Abstract) 



The paper is a result of a field study of the deposits made in July, 1915. 

 The geological and mineralogical relations of the emerald are discussed and 

 evidence presented to show that the emerald originated as a result of gas- 

 aqueous emanations from an intrusion that is not exposed, but is indicated 

 by the presence of contact rocks, pegmatites, and a significant mineral asso- 

 ciation. 



Presented in abstract extemporaneously. 



CRYSTALLINE MARBLES OF ALABAMA 

 BY WM. F. PROUTY 



{Abstract) 



The crystalline marbles of Alabama are largely confined to an area about 

 35 miles long and 1^4 miles in maximum width. This area is for the most 

 part a fault block, with the strike of its rocks in some places similar to and 

 in other places differing from both that of the Ocoee phyllite, which bounds 

 it on the southeast side throughout the length of the field, and the Knox dolo- 

 mite formation, which bounds the field for the larger part of the distance on 

 the northwestern side. Topographically the area is a well defined valley, ex- 

 cept locally, where it is crossed by ridges of dolomite or more resistant rock. 



Although there is no direct fossil evidence to indicate the age of the marble. 

 the general characteristics lead to the conclusion that it varies in age from 

 Cambrian to Ordovician in different parts of the field. 



The thickest deposits of marble are in the central and southwestern parts 

 of the field, and it is here that the chief developments of the area are being 

 made at the present time. 



The quarry methods employed in some of the openings are considerably 



