548 DEPARTMENT OF TEE INTERIOR 



2 GEORGE V., A. 1912 



is clear that, if the zone of Cambrian and ' Belt terrane ' shore-lines was situated 

 in the vicinity of the Columbia river and a large region to the west thereof 

 furnished the clastic material for the Rocky Mountain Geosynclinal, we must 

 not expect to find Cambrian or older marine sediments conformable with the 

 Cambrian in the mountains west of the river (Columbia system and probably 

 the Cascades). 



3. Lithological similarities. — This principle has been the one most used. 

 The fossiliferous Huntingdon, Cultus, Pasayten, and Kettle River formations 

 have, respectively, only one occurrence in the Boundary belt; they cannot, 

 therefore, be used extensively in the direct discovery of horizons in the more 

 widely-spread rocks. The great majority of the latter, however, belong to a 

 number of heterogeneous series, from the Pend D' Oreille group of the Selkirks 

 to the Chilliwack series of the Skagit range. Each series, lithologically 

 variable in itself, has very close resemblance to each of 'the others. The series 

 at nearly the extreme east (Rossland district) carries Carboniferous fossils; 

 the series at the extreme west (Chilliwack district) likewise carries Carbonifer- 

 ous fossils. The correlation of only a few of these series is imperative; for all of 

 them it is merely permissible until paleontological evidence is added to the 

 lithological evidence. 



4. Correlation of the Forty-ninth Parallel formations among themselves, 

 aided by comparison with standard, fossiliferous sections to north and south. — 

 The general correlation of the rocks occurring in the Western Geosynclinal Belt 

 will be discussed on later pages but it may here be noted that the continuance 

 of the Paleozoic belts along their strike brings them into areas where Carboni- 

 ferous fossils have been found in greater or less abundance and always in 

 terranes much like those represented in the Pend D'Oreille, Attwood, Anarchist, 

 aud Chilliwack series. Examples are: the Cache Creek series of the Kamloops 

 district, the Slocan series of the Slocan district, the Wood River series of 

 western Idaho, and the Calaveras series of California. 



5. Correlation of the sedimentary rocks often suggested through the 

 accordant testimony of the relative dates of deformation, metamorphism, and 

 igneous intrusion. — a-. The periods of severe, though not always general orogenic 

 movements which have been proved elsewhere in the Cordillera, are : the pre- 

 Cambrian, Upper Jurassic, early Eocene (post-Laramie)-, and the later Miocene. 

 It seems already highly probable that, with the possible exception 

 of orogenic events in the mid-Carboniferous and at a pre-Devonian, post- 

 Cambrian time, no other periods of strong general deformation will be proved 

 for the Western Geosynclinal Belt through future discoveries, at least so far 

 as concerns the post-Cambrian formations. 



b. Extreme regional metamorphism in this belt, where not increased by 

 the contact-metamorphism of intrusive bodies, is a fairly general indication of 

 the pre-Cretaceous age of the rocks so altered. Wherever the Jurassic or Triassic 

 formations are associated with Carboniferous or other Paleozoic formations 

 within the Western Geosynclinal Belt, the Mesozoic beds are almost always less 



