[G. M. DAWSON] SFX'ULAR CLIMATIC CHANGES 165 



foliage of the trees, but actually cut oil' the bark from exposed positions 

 and sawed into the wood for several inches. An inspection of the branches 

 thus cut showed that the annual rings had formerly perfected them- 

 selves, and that the snow had worn off a considerable portion, often sev- 

 eral inches, of the thickness of the wood, leaving a smooth polished sur- 

 face, displaying the cut edges of the layers of annual growth." From 

 these observations, taken in connection with the age of the trees on the 

 upper part of the mountains, he arrived at the conclusion that the " ex- 

 isting climatic oscillation began before the year 1870, and was the first of 

 its kind for over 250 years." ' This, it will be noted, agrees remarkably 

 well with the evidence afforded by Gilbert's diagram for the Great Salt 

 Lake. 



Facts of a similar kind are not wanting in that part of the Cordillera 

 comprised in British Columbia. Both in the Eocky Mountains and in the 

 Selkirk ranges many recent cases of avalanches or '-snow-slides" which 

 have mowed their way through forests of large trees are found, and each 

 such case must be accepted as showing the occurrence of long unpre- 

 cedented accumulations of snow on the higher slopes. It must, however, 

 be added that there are very many gorges and slopes where no trees 

 api^ear to have grown at any time, in consequence of almost annually 

 recurrent avalanches, and that the exceptional cases in which old trees 

 have been destroyed, are in their nature so striking as to attract perhaps 

 an undue degree of notice. 



It has also been noted, both by the writer and others, on the higher 

 mountains of British Columbia, near the snow-line, that dead trunks and 

 stumps of larger and better grown trees than any now found living in the 

 same situations, frequently occur ; and that in places where the original 

 growth of trees at altitudes approaching 6,000 feet has been destroyed by 

 fire or by storms, it often shows no tendency to renew itself. Mr. J. 

 McEvoy, who assisted Mr. A. Bowman in his surveys of the Cariboo mining 

 district in British Columbia, has furnished the following note on his obser- 

 vations on the point in question in that district : — 



" On many of the higher parts of the mountains in the Cariboo 

 district, the presence of large dead trees is noticeable, where the only 

 living ones are of a very stunted character. These large trees have died 

 long ago, as only the resinous parts remain. This state of things is most 

 marked on the Goose Creek Mountains. The damp climate, with the fact 

 that the Indians do not appear to have hunted in these mountains, make 

 it less reasonable to sup])Ose that fire has been the cause. Even if fire had 

 killed the forest, sufficient time has elapsed for its renewal, and there 

 appears to be enough soil to maintain such growth. A change in climate 

 seems to be the only satisfactory explanation." 



U. S. Geological Exploration of the 40tii Parallel, vol. i., pp. 526-527. 

 Sec. IV., 1896. 10. 



