338 



University of California. 



[Vol. i. 



Geological Survey of Canada.* The geographic and geologic 

 surveys necessary for the preparation of this sheet were under the 

 immediate direction of the writer, and were well advanced at the 

 time of his resignation from the Canadian Survey in 1890. The 

 work was subsequently continued and prepared for publication by 

 the writer's assistant, the late W. H. Smith, acting under instruc- 

 tions from the director of the survey. Although Mr. Smith was 

 thoroughly devoted to his work and was a very competent geog- 

 rapher, his duties as such had, in the earlier years of his service, 

 precluded his giving attention seriously to geological studies, and 

 he therefore undertook the continuation of the writer's work prac- 

 tically as a beginner in geological research. The vigor and ability 

 which he displayed in the execution of that task foreshadowed a suc- 

 cessful career had he been spared to follow up the investigations 

 so inaugurated. 



Mr. Smith being thus unexpectedly called upon to complete a 

 work with which he was familiar, but for which he had had no 

 especial preparation, it is not surprising, nor does it in the least 

 reflect on his memory, that some deficiencies should exist in his 

 account of the geology of the region and in the accompanying 

 map. Some of these may, as opportunity presents, be filled out by 

 the writer, with perhaps better grace than by any other investigator 

 who may follow us in this field. 



Among the more interesting points in the geology of the region 

 which were touched upon, but not fully discussed, in Mr. Smith's 

 report, are the rocks of Poohbah Lake; and it is the purpose of 

 this paper to present some observations upon these rocks which, it 

 is hoped, may have more than a local interest. 



The field data are based on a somewhat hurried but geograph- 

 ically complete examination of the shores of the lake during two 

 days of the last season in which the writer was engaged in explor- 

 ing the region, supplemented, for purposes of mapping, by some 

 observations by Mr. Smith on Wink Lake to the west, and two 

 short excursions by the writer on jungle trails, one from the north 

 shore of the lake northward, and the other from the south shore 

 southward. 



""Annual Report, Vol, V, 1890-91. Part G. 



