BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 
VOL. 9, PP. 223-238 FEBRUARY 24, 1898 
CLASTIC HURONIAN ROCKS OF WESTERN ONTARIO 
BY ARTHUR P. COLEMAN 
(Read before the Society December 29, 1897) 
CONTENTS 
Page 
Results of previous work in the region............. 00 cee cee cece eee erence 223 
(Clacsiticamomuot theyrocky Series... <.5..22 20 ques dermis ge ois scleral a eee 224 
SLUCINCCOMM CANE | ASC Spas tey pays cter eon svel cies scl wy xe 'o enaraus Slot Soqedaue aperasateeneitasl cece ats) Spcntel stew | Recreate 
CGeneralusiatementasttovOrlolm. 4.21.0 game doemisaaeh © once wes 224 
IN@@O AUN, ROC! S aces G Cine ae cre aE eee eee cen ein A ive ator Sale HSI 225 
@onchichime rockst oe... 5++2--.- Byatt Men Ue Se ACS ore AO ae 227 
Relation of Keewatin to Couchiching......... VE Aes Be Bat BRN TES Rees ASV ND UE 227 
MMnekmesshOnUMeVELUTOMIaAM SeTIES)¢.- .22---5.--heuredeedosmenas se seme te aeZS 
Field relations of Laurentian and Huronian.......... ........-.+.s0.----.- 229 
Sections through pre-Cambrian mountains........... .....---.. +--+. 281 
Geological history of the region... ............-.-....- pA eet eet sven Ce 231 
Comipanisonswithvother reoions. 3:25.25. 26. wjeeess see ee ses ae eee one 232 
Cause of these mountain structures .............. 22. cece tee eee eee eee ee 233 
tenor mem babwolitte ReSlOMs:.2...-+- dade ceeic sleigh sia Ustaclame eet oes 235 
Concluding observations ...... SE Ores ek era cae Ro alas ote 238 
ReEsuLtTs oF PREVIOUS WORK IN THE REGION 
The rocks of western Ontario have been more or less carefully exam- 
ined by several geologists, such as Bigsby, Bell, and Dawson, but the 
first detailed mapping of the region was done in 1883 and succeeding 
years by A. C. Lawson, who laid an excellent foundation for the future 
study of the Lake of the Woods and Rainy Lake districts.* Since then 
adjoining districts have been mapped by W. H. C. Smith and W. McIn- 
ness, and special portions have been studied by H. L. Smyth, Winchell 
and Grant, and the present writer. The general conclusions reached by 
Lawson have been commonly accepted by those who have followed and 
will be made use of largely in the present paper, though most of the 
* Geol. Survey of Canada, 1885, part CC ; and 1887, part F. 
XXXIV—Butt. Geor. Soc. Am., Vor. 9, 1897. (223) 
