314 G. M. Dawson — Rocks of British Columbia and Chile. 
mate raore pr less to the type in Yoredale. Considering tke peculiar 
ckaracter of tlie Yoredale beds, so different from the Millstone Grit, 
I tliink it would be a mistake to tbrow tliem into the saine dass as 
the latter group ; nor would Prof. Hüll find it every wbere so easy, 
as it is in Derbyskire and Lancaskire, to separate tlie Upper Lime- 
stone Skales from tke Carboniferous Limestone, tke fact being that 
the tkick limestone splits up north-eastward into a number of sub- 
divisions of limestone, sandstone, and skale. I do not myself 
believe, pace Prof. Hüll, in tke possibility of finding any Classifica- 
tion of tke Carboniferous rocks applicable to tke wkole of England, 
otker tkan tke pkilosopkical one recommended by Prof. Eamsay, of 
treating tke wkole as one indivisible formation and mapping 
separately eack important bed, or group of beds, of grit, limestone, 
ckert, ironstone, plate, or skale. 
VII. — Mesozoic Volcanic Rocks of British Columbia and Chile. 
Relation of Volcanic and Metamorphic Rocks. 
By George M. Dawson, F.G.S., 
of tlie Geological Survey of Canada. 
I N Chile and adjacent regions of South America, Mr. Darwin, in his 
“ Geological Observations,” kas described a great series of Meso- 
zoic rocks, wkicli ke calls tke “ porpkyritic formation,” and whick 
skows an interesting resemblance to certain rocks in British Columbia. 
These I had provisionally designated in my report in connexion witk 
the Geological Survey of Canada for 1875, as tke Porphyrite series, 
witkout at tke time remembering Mr. Darwin’s name for tke Chilian 
rocks. Many of Mr. Darwin’s descriptions of tke rocks of Chile 
would apply word for word to those of British Columbia, wkere tke 
formation would also appear to bear a somewkat similar relation to 
the Cascade or Coast Range, wliich tkat of Chile does to tke Cordillera. 
By its fossils, the porpkyritic formation of Chile is proved to occupy a 
position intermediate between tke Jurassic and Cretaceous, whick is 
muck that whick tke Porpkyrites of British Columbia must hold. 
Beds overlying tke Porpkyrites on Tattayoco Lake by some tkousands 
of feet — probably conformably — hold fossils ckaracteristic of tke 
Sliasta Group or lowest of tke Cretaceous in California, whick is 
believed to represent the Englisk Series from tke Gault downwards. 
Fossils collected last summer in tke porphyrite and felsite — altered 
ask rocks — of tke Iltasyonco, a brancli of tke Salmon River in latitude 
52° 50', present a more distinctly Jurassic facies, tkougk tkeir 
palaeontological value will be more certainly known wken Mr. 
Wkiteaves skall kave finisked kis examination of tkem. 
Of tke South American Series Mr. Darwin writes: 1 — “Tke 
alternating strata of porpkyries and porpkyritic conglomerates, and 
with tke occasionally included beds of felspatkic slate, togetker make 
a grand formation ; in several places witkin tke Cordillera I esti- 
mated its thickness at from 6000 to 7000 feet. It extends for many 
kundred miles, forming tke western flank of tke Chilian Cordillera ; 
1 Loc. cit. p. 476. 
