THE LOWER HURONIAN. ■ 333 



of the red bands and tlie gray chert bands, these rocks simulate the jaspers 

 and cherts of the iron formation proper. A somewhat similar occurrence is 

 that noted at the south end of the portage coming into the north side of 

 Pickle Lake, where there are alternating slate and purplish chert bands, 

 striking N. 35° E. in the midst of the Knife Lake slates. These are 

 probably the continuation of similar chert bands which occur upon the 

 southeast shore of Pickle Lake. 



On the bare hills crossed by the Wind Lake-Moose Lake portage 

 tnere are good exposures of the iron-bearing Agawa formation, showing 

 its relationship to the adjacent rocks. To the north is a conglomerate 

 consisting of greenstone pebbles with occasional pebbles of acid rocks, feld- 

 spathic porphyry, rhyolite-porphyry, and granite. Above the conglomerate 

 is about 3 feet of coarse graywacke and fairly coarse slate, followed by a 

 belt about a foot and a half in thickness, in which the interbanding is closer 

 with the slate predominating. Then comes 3 feet of the iron-formation 

 member, consisting chiefly of the black chert — black jasper as, it is some- 

 times called — greenish chert, and some red jasper, although this is in rather 

 subordinate quantity. With these cherts there are found a few fine-grained 

 slaty layers ranging in thickness from a fraction of an inch to 4 inches. 

 This band of the iron-bearing formation is 6 feet wide. South of this iron- 

 bearing formation, and making up the remainder of the section of this hill, 

 and exposed for a hundi-ed feet or more, across the strike, is a conglomerate 

 similar to the conglomerate below the jasper band in its essential characters, 

 but different from it in several important respects: First, it contains several 

 narrow but minutely crenulated complex layers of interlaminated gray- 

 wacke, slate and jasper; second, it contains many roundish, lenticular, and 

 also angular areas of black chert, red jasper, and a black slaty-looking 

 jasper, and various combinations of these. When these areas are examined 

 closely, they appear to be true beds which have been broken by dynamic 

 action. The undoubted jasper formation itself is extremely crenulated and 

 broken. Generall}^ the pebble-like areas continue out into thin strings 

 which may be connected with laminse of jasper, but this is not invariably 

 the case. If the jasper is in true fragments the slate and graywacke also are 

 in true fragments, for they, too, occur in this material in similar roundish or 

 angular masses. It has been suggested that this conglomerate lying above 

 the jasper belt first described is younger than the jasper, and that these 



