PLAN OF FIELD WORK. 3 
Michipicoten, and kindly sent me by the Director of the Geological Survey 
of Canada, help to supply this deficiency in some measure. 
My plan of field work, as carried out, included: (1) a study of the 
north shore of the lake from Duluth to Nipigon Bay, including excur- 
sions up the principal streams for distances of from five to twenty niles ; 
(2) a trip from Grand Marais, on the North Shore, northward and westward 
to the headwaters of Cascade and Brulé Rivers, including an examination 
of the country about Brulé Lake and Eagle Mountain, a region never be- 
fore visited by any geologist; (8) a very rapid examination of the east 
coast from the Sault to Mamainse; (4) a study of the well-known mining 
region of Keweenaw Point, including the little-known district in the 
vicinity of Mount Houghton; (5) a comparatively thorough examination 
of the Porcupine Mountains, a knowledge of whose hitherto unknown 
structure was necessary to the understanding of that of the entire lake 
basin; (6) an examination of Silver Mountain, southwest from L’Anse; 
(7) a rapid exploration of the “‘South Copper Range,” eastward from Lake 
Agogebic; (8) an examination of the valleys of the Kettle and Snake 
rivers in Minnesota, with the view of determining the extent of the copper- 
bearing rocks in that direction, and the manner in which they terminate 
westward; (9) an examination of the valley of the Cloquet River to its 
junction with the Saint Louis, and of the latter stream from this junction 
to its mouth. 
Such extended investigations could not be all carried out in person 
in one season. My own immediate attention was given to the north 
shore of the lake from Duluth to Nipigon Bay, to the region of Portage 
Lake and Mount Houghton, and to the region south of Ontonagon. In 
the other work I was aided by Messrs. W. M. Chauvenet, A. C. Camp- 
bell, R. McKinlay, L. G. Emerson, and B. N. White. Messrs. McKinlay 
and Campbell made the river trips between Duluth and Grand Marais; 
Messrs. Chauvenet and McKinlay together examined the country from 
Grand Marais to Brulé Lake, and the valleys of the Cloquet and Saint 
Louis Rivers; Mr. McKinlay alone examined the valleys of the Snake and 
Kettle Rivers; Mr. A. C. Campbell made the trip from the Sault to Ma- 
mainse; Messrs. Chauvenet and White together studied the eastern half of 
