108 A. P. COLEMAN — UPPER AND LOWER HURONIAN IN ONTARIO 



grade brown hematite north ofWawa lake, some miles inland, has aroused 

 fresh interest in the region, and has resulted in the tracing up for many 

 miles of a, hand of silicious rock interleaved with thin sheets of iron ore. 

 in many respects much like the famous iron ranges of Michigan and 

 Minnesota. The rock has generally the aspect of a sandstone, but thin 

 sections prove that it is not an ordinary sandstone, in spite of the fact 

 that many parts of it crumble to fine grains under the fingers; for the 

 grains of quartz have polygonal forms that meet in planes, but are only 

 loosely, if at all, cemented. The grains are often six-sided, and in thick 

 sections show a rough dodecahedral shape, the result probably of growth 

 outward from numerous nearly equidistant centers until the grains met, 

 just as spheres crushed together tend to take on a dodecahedral form.* 



The usual variet} T resembling sandstone sometimes passes into a rock 

 like chert or in other cases jasper, and occasionally takes the appearance 

 of quartzite. In many parts of the range the interbanded sandstone and 

 magnetite or hematite are more or less brecciated, and have undoubtedly 

 undergone great folding and crushing. The band now stands nearly 

 vertical in most regions to which it has been followed. 



This band of rock is usually thin, not more than a few hundred yards 

 in width, and there are numerous interruptions in its outcrop, due prob- 

 ably to weathering, for the sandstone variety is so fragile that in river 

 valleys it has been cut down faster than other rocks and is often lost to 

 sight under the thick drift deposits of the region. This probably ac- 

 counts for the fact that it was overlooked until last summer, since the 

 region is without roads and hitherto had been explored almost entirely 

 with canoes. 



The cherty and jaspery varieties, however, stand weathering excel 1 

 lently and form ranges of hills easily followed. The ore bodies found 

 associated with the sandstone are of considerable variety, magnetite of 

 low grade being commonest, though soft red hematite and hard and soft 

 iimonite occur also, the latter, in the case of the Helen mine, amounting 

 to hundreds of thousands of tons of exceptionally pure ore. None of the 

 deposits have } r et been sufficiently explored to determine their extent. 



It is almost certain that this band of silicious rock charged with iron 

 ore is of sedimentary origin, although perhaps not clastic, but rather 

 deposited chemically. 



Extent of the Iron Range 



The band of sandstones and jaspers containing iron ores, though so 

 narrow, has already been followed for more than 50 miles, of course with 



*ct'. [rving anil Van llisc, Penokee Iron Bearing Scries, i T . s. Geol. Sur., monograph xix, p. 133, 

 etcetera, where the grains seems to be described as crystals rather than unoriented polyhedra. 



