Methods of Stratigraphy. — Wine hell. 355 
ed reports and other papers of the early geologists in forming 
an opinion as to what they believed, rather than by interpre- 
tations and traditions that have grown up from them. It is 
intended here only to call attention to the improved methods 
of work. These consist of the following, as distinguished from 
the old methods : 
1. Painstaking field-work, extended and repeated over a 
small area, map in hand, accompanied by descriptions and 
sketches made on the spot. 
2. Sampling of all changes in rock-species from place to 
place with notation in the field, referring each sample to its 
place in the accompanying field descriptions. 
3. Chemical and microscopic examination of the samples 
in the laboratory. 
4. Combination of field-studies with laboratory work, and 
the publication of the results. 
These methods have been pursued in some parts of the 
Northwest, at different times recently, by different geologists in 
some of the areas that have been included in the expanded 
conception of the Huronian, with surprisingly concurrent re- 
sults. Without mentioning the work of the Minnesota survey 
which is not yet carried to completion, I shall refer only to the 
examination of the rocks in the vicinity of Sudbury, by T. G- 
Bonney in 1886," the thorough microscopic work of Prof. R" 
D. Irving, accomplished for the United States geological sur- 
vey,'^ and his discussion of the elements of Huronian strati- 
graphy published recently in the Seventh annual report of the 
same survey, and to the work and results of Dr.A.C. Lawson of 
the Canadian geological survey, in the regions of the Lake of 
the Woods and Rainy lake, on the international boundary line 
west of lake Superior.'" 
Similarly accurate field-work has also been done in Michi- 
gan by Dr. C. Rominger,'' resulting in a similar correction of 
the early survey of major T. B, Brooks. 
'Hiuart. Journ. Geol. Hoc. London, Mav 1886, p. 83. 
'^Tiiird Annual Report, U. S. Geol. Sur. 1881-82, pp.93-180 Mono- 
f;raph No. v. The copper-bearing rocks of lake Superior, 1883 ; Bulle- 
tins No. 8 and 23. 
'"Report on the geology of the Lake of the "Woods, with special ref- 
erence to the Keewatin (Huronian?) belt, of the Archa'an rocks. A. 
C. Lawson; 1885; Reports of progress of the Canadian survey for 1885. 
Also Geology of the Rainy Lake region ; Reports of the Canadian sur- 
vey for 1887.' 
'"Geological survey of Michigan, Upper Peninsula, 1878-80, Vol. iv. 
