MICHIGAN ACADEMY OP SCIENCE. 
59 
RIPPLE MARKED HURONIAN QUARTZITE AT NIPISSING 
MINE, COBALT, ONTARIO. 
(With six plates). 
BY REGINALD E. II ORE, MICHIGAN COLLEGE OF MINES. 
At tlie Nipissing Mine, an unusual method of surface prospecting has 
presented remarkably well exposed areas of Huronian and Keewatin 
rocks. In examining these areas recently, the writer found the well 
developed ripple marks shown in the accompanying photographs. Being- 
very well preserved, the marks are of interest in themselves. As they 
occur in a series of rocks supposed to he largely of glacial origin, they 
have added interest. 
Of the Huronian rocks at Cobalt, the most characteristic type is a 
coarse conglomerate, sometimes called the Cobalt conglomerate. The 
unusual characters of this rock were pointed out by Dr. A. P. Coleman, 
who showed 1 that the material was probably of glacial origin. In a 
subsequent paper in the Journal 2 the present writer gave additional in- 
formation in support of Dr. Coleman's view. It was stated that, with 
the conglomerate, there is well stratified material, and to this was as- 
cribed a glacio-fluvial origin. At the time of writing that paper, the 
writer had not seen any ripple marks ; but the evidence of deposition of 
some of the material by water was regarded as quite conclusive. More 
recently ripple marks have been found in the rocks broken in mining 
the silver ore; but until the hydraulic work was done at the Nipissing, 
it was not possible to present photographs showing the marks on rock 
in place. In prospecting the surface at the Nipissing Mine, a powerful 
stream of water, 4800 gallons per minute from a 3% inch nozzle, is 
directed against the glacial debris and the rocks washed bare. The 
photographs show Huronian rocks thus exposed. Fig. No. 1 shows an 
end view of the quartzite bed which has the rippled upper surface. Fig. 
No. 2 shows a thin layer of shaly mud rock lying on the ripple-marked 
quartzite. Fig. No. 3 shows a large boulder in the fine mud rock lying- 
on the quartzite. Evidently, there were remarkable changes in local 
conditions, for these large boulders encased in fine mud rock, or shaly 
greywacke, lie immediately on top of the bed of uniformly grained 
quartzite. Fig. No. 4 shows, at the left, blocks of the mud-rock which 
overlies the quartzite. Figs. No. 5 and No. 0 show closer views of the 
quartzite. 
'A. P. Coleman. Lower Huronian Ice Age. Jour. Geol. Vol. XVI. No. 2, pp. 149-158. 1908. 
2 Glacial Origin of Huronian Rocks of Nipissing. Jour. Geol. Vol. XVIII No. 5, pp. 459-467. 1910. 
