514 DEPARTMENT OF THE INTERIOR 



2 GEORGE V., A. 1912 



West of Thurston's ranch the crinoidal limestone seems to be repeated by 

 a strike-fault, the beds retaining their general northeasterly dips of from 20° to 

 60° or more. This attitude is fairly well preserved in the outcrops along the 

 river trail all the way to the mouth of Tamihy creek. The welter 

 of forest, brush, and moss, as well as a heavy mass of Glacial drift on the river- 

 valley floor, prevent any accurate conception of the nature of the beds crossed 

 in this seven-mile traverse down the river. It is probable that the rocks corres- 

 ponding to members e, f, g and h of Section III. are represented in this section 

 or have been faulted out of it and that the very thick, phyllitic argil! ite seen 

 along the north bank of the river at and just above the confluence of Tamihy 

 creek with the river, is an older member of the series than any of those so far 

 mentioned. Nothing better than a guess as to the thickness of this member is 

 possible but 1,000 feet is apparently a very safe minimum. 



The pillow-lava and agglomerate of Section IV. seem to represent the lower 

 part of the great volcanic member e, of Section I. The adjacent rocks match 

 the respective members of Section I. in a rough way; considering that contin- 

 uous exposures were not to be found at either locality, an exact correspondence 

 sbould not be expected. 



General Columnar Section. — Combining the facts determined in these four 

 sections with the many scattered observations made elsewhere, the following 

 table may be made to express the writer's tentative conclusion as to the anatomy 

 of the Chilliwack series : — 



Top, erosion surface at plane cf unconformity with the Tamihy (Cretaceous?) 



formation. 



1. 50 + feet. — Quartzitic sandstone. 



2. 20 " Dark gray argillite. 



3. 50 " Light gray limestone; fossils, Nos. 1506, 1509, 1510. 



4. 60h= " Gray calcareous quartzite and argillite. 



5. 2,000 + " Andesitic flows, tuffs., and agglomerates (pillow-lava probably in this 



member where locally developed). This member may for conven- 

 ience be referred to as the Chilliwack Volcanic formation. 



6. 200 " Gray and brownish shale and sandstone, with thin conglomerate 



bands ; shales crumbling and thin-bedded ; highly fossilif erous. 

 Fossils Nos. 1,512 and 1,514. 



7. 600Hr " Light gray, massive, generally crystalline limestone, often crinoidal; 



with fossils No. 1513 (crinoidal fragments also represented in Nos. 

 69, 70,71, 72, 98, 129). 



8. 90 " Shale, sandstone and grit. 



9. llO-i- " Massive light gray limestone, with large crinoid stems and fossils as 



No. 104 (not collected here). 



10. 300-1- " Dark gray and brown shales, with fossils, No. 104. 



11. 100 " Massive, hard sandstone. 



12. l,400rt " Hard sandstones and black and red shales with bands of grit and 



thin beds of conglomerate; thickness very roughly estimated. 



13. SOOrfc " Hard, massive sandstone with gritty layers. 



14. 1,000 + " Dark gray to black, often phyllitic argillite with quartzitic bands. 



6,780+feet. 



Base concealed. 



Geological Age \pf the Series. — As already indicated, the lower members 

 of the Chilliwack series may belong to one or more systems older than that 



