Section IV., 1896. [ 159 ] Tkans. R. S. C. 



X. — Some Observations Tending to show the Occwrence of Secular 

 Climatic Changes in British Columbia. 



By Ct. M. DawsoiV, C.M.G., F.R.S., LL.D., Director of the 

 Geologietxl Survey of Canada. 



(ReadMay 20, 1896.) 



In a report by the writer on a portion of the Rocky Mountains, 

 proper, comprised between latitudes 49° and 51° 30', the following remarks 

 occur,' referring particularly to the years 1883 and 1884 : — 



'' Evidence of a remarkable character has been found, which seems 

 to show that a somewhat rapid increase in the total annual precipitation, 

 has taken place during late years, and deserves to be recorded here. The 

 evidence referred to is that afforded by the abnormal height of small 

 lakes, without outlets, occurring in regions characterized by moraine 

 hills. These serve as natural gauges, but instead of measuring the actual 

 rainfall, give a result dependent on this and the counteracting effect of 

 evaporation. The abnormal character of the rise of water in these lakes 

 is shown by the fact that it has killed a belt of trees, some of large size 

 and at least fifty years in age, along parts of the margins of some of these 

 lakelets. Both the Douglas tir {Pseudotmga Dow/lasii) and the yellow 

 pine {Pinus ponderosa) — the latter never naturally growing even in 

 damp soil — have been found in numbers thus killed. The condition of the 

 trees shows that they have been killed within a few years, and their, size 

 indicates that the waters of the lakes in question have not been for any 

 considerable time during a period of fifty years or more, at the present 

 high level. These observations were made both in 1883 and 1884. The 

 lakelets observed to be so affected were numerous, and scattered over a 

 belt of country along the western part of the range for a length of about 

 140 miles ; three of the principal districts in which such facts were noted 

 being the Tobacco Plains, the Kootanie Valley between the Lussier Eiver 

 and head of Columbia Lake, and the upper valley of the Kootanie, near 

 the mouth of the Vermilion." 



It was further recorded, that most of the small streams flowing 

 westward from the Rocky Mountains iit the same region, showed signs of 

 excessively heavy flood-water in the early part of the year 1884. " This 

 evidence was of such a character in relation to trees of great age which 

 had been undermined, and belts of wood through which the water had 

 rushed with devastating force, that I was led to believe no such flood 

 could have occurred for fifty or a hundred years previously." 



• Annual Report, Geol. Surv. Can., 188.5, p. 32 B. 



