522 C. K. LEITH 



Peridotite is found in one exposure only in this valley, three miles 

 southeast of Morton. The relations to the other rocks of the area 

 could not be determined. Cutting the gneisses and gabbro-schists 

 throughout the area are numerous dikes of diabase. They vary in 

 width from a fraction of an inch to 175 feet. Their age is probably 

 Keweenawan. 



Southeast of Redstone and near New Ulm are exposures of quart- 

 zite associated with coarse quartzite conglomerate. Near Redstone 

 the strike of the quartzites is N. 60-70 W., and their dip varies from 

 5-27 N. In New Ulm the strike is N. 15 E., and the dip varies 

 from 10-15 S. E. The quartzite is believed to be the same as the 

 quartzite found in a deep well at Minneopa Falls, near Mankato, 

 Minn., which is covered by a quartzite conglomerate of Middle Cam- 

 brian age. The quartzite of Redstone and New Ulm is above the 

 Archean granite and gneiss. It is believed to be of Huronian age, 

 but whether Upper or Lower is unknown. 



Overlying the crystalline rocks are Cretaceous shales and sand- 

 stones, which appear in rare exposures in the valley, and glacial drift. 



Coleman 1 discusses areas mapped by Logan as Huronian north of 

 Lake Huron and the east end of Lake Superior. The two contacts 

 described by Irving and Van Hise as contacts of the Lower Huronian 

 and Laurentian rocks were examined. At the first, on the islands four 

 miles east of Thessalon, jasper and chert fragments were found in the 

 conglomerate above the Laurentian, indicating that the conglomerate 

 is probably a part of an upper series, younger than a series of rocks, 

 not Laurentian, from which the jasper must have been derived. At 

 the other contact, on the road between Sault Ste. Marie and Garden 

 River, it is concluded that the conglomerate is possibly a crushed con- 

 glomerate formed by faulting instead of a water-formed rock. 



Certain green and gray schists inclosed in the Laurentian gneisses 

 are believed to represent the western Keewatin of Lawson. 



The Laurentian and Huronian contact at Goulais and Batchawana 

 bays was found to be in general of the nature of an eruptive contact, 

 although a clear example of the inclusion of a typical Huronian rock 

 in the Laurentian was not observed. 



The slate-conglomerate of Dore River contains no bowlders that 

 are distictly Laurentian. It contains only fragments of schists and 



'Copper Regions of the Upper Lakes, by A. P. Coleman : Rept. of the Bureau 

 of Mines, Ontario, Vol. VIII, Pt. 2, 1899, pp. 121-174. 



