85 
A TRIASSIC CORAL REEF FAUNA IN BRITISH COLUMBIA 
By Hervey W* Shimer 
CONTENTS Page 
Introduction 85 
Description of fossils 85 
Correlation and conclusions as to age 88 
Illustrations 
Plate IX. Illustrations of fossils 151 
INTRODUCTION 
The Upper Triassic fossils from Bridge River area, B.C., herewith 
described, and correlated with the Sutton formation of Vancouver island, 
were collected during the summer of 1920 by W. S. McCann of the Geologi- 
cal Survey. According to McCann 1 they occur in small lenses of black 
limestone in arenaceous and argillaceous shales in the upper part of a 
series which, in ascending order, consists of conglomerate, sandstone, 
and shale with, in the lower part, great thicknesses of basaltic and andesitic 
greenstones. The whole series as exposed has a thickness of about 2,100 
feet and forms the Cadwallader series. Intrusive into the Cadwallader 
series are stocks of augite diorite and bodies of quartz diorite. The lime- 
stones have thus been subjected to considerable metamorphism to the 
detriment of the included fossils. 
The limestones in which the fossils were found occur on Pearson creek, 
a tributary of Gun creek which joins Bridge river. This locality is 150 
miles north-northeast of the type locality of the Sutton formation 2 on 
Cowichan lake, Vancouver island. At the type locality the Sutton con- 
sists of pure limestones (i.e. coral reefs, coquina of pelecypods, and cal- 
carenite of fragments of these) interbedded with lavas. The Pearson 
Creek limestones are a rather pure lime mud in which are entire pelecypods, 
gastropods, brachiopods, and corals, the last rather fragmentary. The 
kind of limestone, the fossil remains, and the associated sands and argil- 
laceous muds indicate a deposit much nearer shore than at the type locality. 
DESCRIPTION OF FOSSILS 
Isastrea whiteavesi Clapp and Shimer 
Our single specimen of some 20 corallites agrees with the type. 3 It 
agrees very closely also with 7. profunda Reuss 4 from the Zlambach fauna 
in size and shape of corallites, but differs slightly in its smaller number of 
septa (24 instead of 24 to 40) and in apparently having merely granules 
instead of spines upon the sides of the septa. 
1 McCann, W. 8., "Geology and Mineral Deposits of the Bridge RiveT Map-area, British Columbia," Geol. 
Surv., Canada, Mem. 130, pp. 28-20, 1922. 
* Clapp, C. H., and Shimer, H. W., “The Sutton Jurassic of the Vancouver Group, Vancouver Island,” Proc. 
Bbston Soc. Nat. Hist., 34, pp. 425-438, 1911. 
* Loc. cit., p. 429. 
4 Freeh, F., "Die Korallenfauna der Trias," FaUeontographica Bd., 37, p. 21, Taf. 5, figs. 1-3. 
