lxx GENERAL SUMMARY OF SCIENTIFIC AND 



that we have in the West the evidences of a gradual passage 

 from the cretaceous to the tertiary beds, and that even in 

 these latter it is not easy to distinguish definitely between 

 eocene and miocene, so that what is regarded as one of the 

 greatest breaks in the geological succession is here filled up. 

 With the elevation came a contraction of the oceanic areas in 

 which the animals of the cretaceous lived, while the tertiary 

 life appeared on the higher levels, and slowly found its way 

 down to the plains. So it happened that in Vancouver's Isl- 

 and plants which Heer regarded as miocene were washed into 

 a sea holding cretaceous shell-fishes, and in the Fort Union 

 lignite-bearing group cretaceous reptiles occur with remains 

 of plants which appear to be unquestionably tertiary. These 

 apparent anachronisms are, however, as remarked by Daw- 

 son, perfectly natural, and are to be expected whenever we 

 meet with a true o;eolo<neal transition. 



The evidence derived from the study of these beds of lig- 

 nite shows that they are not due to accumulations of drift- 

 wood, but are the remains of a vegetation which grew on 

 the spot ; they in some cases rest upon beds of under-clay 

 with imbedded roots. With these beds of lignite are also 



cd 



associated layers and nodules of carbonate of iron like those 

 found in older coal formations, and also beds of gypsum. Al- 

 len and G. M. Dawson have both of them lately described 

 anew the curious pseudo- volcanic scoriaceous products which, 

 in a great number of places in this formation, have resulted 

 from the combustion of the lio-nites and the fusion of the 



CD 



overlying strata. 



The evidences of immense erosion over the vast Rocky 

 Mountain region are strikingly set forth by Hayden, accord- 

 ing to whom the entire series of strata, from the lowest pale- 

 ozoic to the highest tertiary, once extended in an unbroken 

 mass over the whole Northwest, and is still seen entire in 

 some places, as in the Cinnabar Mountains. From 10,000 to 

 15,000 feet of strata have been cut away, but portions of com- 

 pact paleozoic limestones are found scattered over the Rocky 

 Mountains at elevations of from 10,000 to 12,000 feet above 

 the sea. 



The immense volcanic outbursts of later tertiary time, which 

 are so conspicuous in the geology of the Western coast, have 

 been discussed anew by Joseph Le Conte. Extending from 



