[PENHALLOW] NOTES ON TERTIARY PLANTS 63 



determination immediately rai^ed certain questions which required 

 soiution: — 



1st. — What deposits are represented by tlie Mystic lake beds, in 

 wliioh the tree was found? 



2nd. — What is the relation of the specimen to the vegetation of the 

 region at the present day, and especially to the distribu- 

 tion of the genus as now known ? 



The occurrence of Pseudotsuga in the fossil state is of exceptional 

 interest, from the fact that the genus has been wholly unknown, especi- 

 ally through its wood, until 1901, when a specimen was brought to light 

 from the Cariboo mine on the Horsefly river, British Columbia, repre- 

 senting the Miocene formation.^ More recent studies have shown that 

 wood of the same species also occurs in the Lignite Tertiary of the 

 Great Valley and Porcupine Creek series of Assiniboia, thereby indicat- 

 ing that P. miocena, Penh., extends from the Eocene info the middle 

 Tertiary, with a somewhat wide geographical range. ^ While it is at 

 present difficult to establish the absolute identity of this latter species 

 with the one now existing, there is a probability that the two are in 

 reality the same, in which case it would be possible to show that P, 

 douglasii ranged through the entire Tertiary formation, since the Boze- 

 man specimen unquestionably represents later Tertiary without refer- 

 ence to its particular horizon; and from this it becomes evident that 

 the existing species in all probability extends back to, and presumably 

 into Cretaceous time, where its remains should be looked for. 



With respect to the geological age of the Mystic lake beds, it is 

 very difficult to draw any final conclusions from this isolated specimen, 

 which might indicate a very recent deposit quite as well as one of Inter- 

 glacial age, as suggested by the formation itself. But in this con- 

 nection we are confronted with the fact that at such an altitude as that 

 of Mystic lake there may have been local interglacial periods at varying 

 intervals, which were not in any way correlated with the continental 

 Tnterglacial period. A request for further information as to the 

 geological age of the deposits elicited the statement from Mr. W. H, 

 • Weed, of the U.S. Geological Survey, that " the material in Mystic 

 lake may be of any age, possibly much later than Interglacial.'' He 

 thinks that glacial activity in that region may have (possibly did) con- 

 tinued until comparatively recently, and that it is risky to make the 

 deposit fit into the standard time scale. 'Tt must be as old as the Tn- 

 terglacial, though there is no evidence against its being relatively recent, 



Cret. & Tert. Plants of Canada, Trans. R.S.C., VIII. , iv., 69. 

 Tert. Plants, Trans. R.S.C., IX., iv., 47. 



