(GEOLOGICAL EXPLORATIONS AND LITERATT^RE. 9 



use of in tlie present volume. Tlie routes followed, so far as tliev traverse 

 our present district, and the exposures located are all indicated on the 

 detailed maps herewith. The writer's visit to this district in ISSf) was made 

 part!}' for tlie jnirpose of supervising the field work then going on under 

 Prof C". R. Van Hise for the U. S. Geological Survey and jiartly for the 

 purpose of studying in detail certain points along the contact between the 

 iron-bearing series and the gneissic rocks south of it. 



Wight, Sweet, and Wright (1875).— In 1875 the coutrol of the Wisconsin 

 Creological Survey passed into the hands of Dr. O. W. Wight. By his 

 order Messrs. E. T. Sweet and C. E. Wright made together an extended 

 geological reconnaissance in northern Wisconsin, being accompanied by 

 the chief geologist in person.' In the course of this reconnaissance the 

 party crossed the Penokee range at the passage of Bad river, where a 

 cross-section of the iron series was attempted. The results obtained Avere 

 sul)sequently published in biief by Mr. Sweet." 



Wright (1876).— In January, 1876, Dr. Wight was superseded in the direc- 

 tion of the Wisconsin Survey by Prof. T. C. Chamberlin, who invited Mr. 

 Wright to contiulu' liis study of the western portion of the Penokee range, 

 with particulat- reference to the occuri'ence there of iron ores. Accordingly 

 Mr. Wright, accompanied by Mr. F. H. Brotherton, a well known lake 

 Superior woodsman and explorer, spent the weeks from August 22 to 

 October 3, 1876, in making a detailed examination of that portion of the 

 iron series lying between Bad river and lake Numakagon. j\Ir. Wright's 

 results^ were published in tlie form of an itinerary, as below noted, accom- 

 panied by a series of maps showing the positions of rock exposures, etc. 

 Mr. Wright's routes of ti-avel and the exposiu-es located by him are platted 

 on the detailed maps accompanying the present volume. 



Chamberlin (i877).-In the fall of 1877, Prof T. C. Chamberliu, accom- 

 panied by A. D. Conover, carried the detailed mapping of the Penokee 



' Geol. of Wis., vol. 11, pp. 72-79. 



* Notes on the Geology of Northern Wisconsin, lYans. Wis. Acad. Sci. and Letters, vol. iii, 

 pp. 40-53. 



'Annual Report of Progress and Results of the Wisconsin Geological Survey for the year 1876, 

 pp. 18-23. Also (ieol. of Wis., vol. iii, pt. iv, pp. 239-301. 



