THE GEOLOGIC SURVEY OF CANADA 



5 1 



: . ■ . ■ ■ 



^^_ 



i«? or ai»ska 



tratlng progress of explorations 

 up to 1904 . 



Rcutes cf exploration by 

 U- S. Cecloelcal purvey. 



,'r^aci cf rt-connalesance surveys 

 by !' . S. Geolcflcal Survey. 



Areas of detailed surveys 

 by U. S. Geological Survey 



Areas surveyed cr explored 



by U. C- Coaet Survey, U. S. Army 



etc., etc 



1A. Map of Alaska, showing unexplored areas in 1895 



accurate reconnaissance map, with elevations indicated by contours; 

 but where time pressed, a canoe traverse, with estimated distances, was 

 substituted. Fortunately it proved possible to carry a rough triangu- 

 lation, checked by latitude and azimuth observations, throughout much 

 of the explored regions. The topography was sketched, on a field scale 

 of about three miles to the inch, with the aid of a plane-table. Altitudes 

 were determined as far as possible by vertical angles, but in many 

 instances depended solely on the readings of aneroid barometers. 

 Contours were sketched at intervals of 200 feet, or, if the topography 

 was very rugged, 500 feet. In some cases it was possible to run stadia 

 lines along the rivers, and salient topographic points were located by 

 intersections. Though some of the journeys were accomplished under 

 exceeding difficulties, in no instance were the surveys entirely inter- 

 rupted. 



The movements of the party were guided more by the requirements 

 of the topographic than of the geologic surveys, and the geologist was 

 perforce required to get such information as he could. Continuous 

 series of notes were kept and specimens were assiduously collected. 

 Special attention was given to the occurrence of placer gold and other 

 metalliferous deposits, but all phases of geologic problems were studied 

 as far as circumstances would permit. Probably the most important 

 scientific results were those that had to do with the general physio- 

 graphic problems. In most cases only the broader features of the 

 stratigraphic succession could be determined, but even these results, 



