78 THE GEOLOGY OF MINNESOTA. 



[Method of lalicliiiK 



1895. J. MORGAN CLEMENTS : The Volcanics of the Michigamme District of Michigan. Journal of 

 Geology, vol. iii, pages 801-822. 



1895. N. H. WINCHBLL : The Origin of the Archean Greenstones. Twenty-third Annual Report of 

 the Minnesota Geological Survey, pages 1-32. 



ABBREVIATIONS 



Ref. References. 



Meg. Megascopic characters. 



Mic. Microscopic characters. 



The method of labeling the specimens collected has been found very safe and perma- 

 nent. It consists in mixing a solution of common shellac, such as can be got of a 

 druggist, with some coloring material, and carefully placing the numbers on the 

 specimens by hand. The alcohol rapidly evaporates from the shellac, which hardens, 

 embracing the coloring material in the hardened mass. Such labels maintain their 

 color and are insoluble in water. Specimens have been numbered as below. 



The regular museum series, rocks, minerals and fossils, have their numbers in 

 red, produced by mixing the shellac with " vermilion red." 



The series of N. H. Winchell are marked with blue numbers, produced by mixing 

 "indigo blue" with the .dissolved shellac. Series from No. 1 to No. 2280. (These 

 numbers are sometimes nearly or quite black.) 



The series of A. Winchell are numbered in black. A mixture of shellac with 

 India ink, and the figures also are followed by the letter W. Series from No. 1 to 

 No. 990. 



The samples collected and reported by H. V. Winchell are marked _pm&, formed 

 by a mixture of vermilion red and white lead, and the numbers are followed by the 

 letter H. Series, No. 1 to No. 542. 



The samples collected by U. S. Grant are marked green, made by mixing Paris 

 green with shellac, and the numbers are followed by G. Series, No. 1 to No. 1067. 



The specimens of J. E. Spurr are numbered in cream irliilc, and the numbers 

 are followed by the letter S. Series, No. 1 to No. 231. 



The specimens of A. D. Meeds are marked in cream white, and the numbers are 

 followed by M. Series, No. 1 to No. 46. 



The specimens of A. H. Elftman are marked in white, and the numbers are 

 followed by the letter E, the series continuing from No. 1 to No. 767. 



GENERAL INDEX TO THE GEOGRAPHICAL LOCATIONS OP THE ROCK- NUMBERS OF N. II. WINOHRLL. 

 [The exact locations are given in connection with the descriptions.] 



NOB. 1 to 293. Along the shore of lake Superior from Duluth to Pigeon point. 



Nos. 293 to 435. From Grand Portage north and west along the international boundary to Burntside 

 lake, thence to Vermilion lake and the Squagemaw bridge (at Embarras lake). 



Nos. 436 to 442. Eastward from the Embarras lake, on the Mesabi Iron range. 



Nos. 443 to 510. Prom Fond du Lac to Knife falls. 



Nos. 511 to 641. From Duluth to Pigeon point, Isle Royale, Silver Islet (Thunder Bay) and return to 

 Duluth. 



Nos. 642 to 796. From Grand Marais northwestward to Ogishke Muncie lake, and thence southwestward 

 to the mouth of Poplar river. 



