60 ROYAL SOCIETY OF CANADA 



The associated rocks are red Hospital Hill slate and gray sand- 

 stone or soft quartzite. The sheets of banded silica generally seem 

 to be interbedded with the other rocks as if belonging to the succession, 

 but sometimes they are locally crumpled, though the rocks above and 

 below seem undisturbed. The adjoining rocks are much less consoli- 

 dated and metamorphosed than those enclosing our Keewatin 

 iron ranges; but banded silica belonging to the Animikie (upper 

 Huronian) in America occurs with somewhat similar slate and soft 

 quartzite. 



The banded siliceous rock of Hospital Hill has been called " calico 

 rock/' and is briefly described by Hatch and Corstorphine in papers 

 on the geology of the Eand.^ Prof. Hatch puts the Hospital Hill 

 slate near the top of the "Witwatersrand system, which overlies uncon- 

 formably the Swaziland beds, looked on as Archœan. According to 

 this succession the banded rocks are later than the Keewatin, but per- 

 haps not later than the Animilde. 



Banded silica with iron ore occurs also in jSTatal, associated with the 

 Barberton series of slates or schists, placed by the Katal geologists in 

 the Archœan. My only specimen, from K'Gotsche mountain, is partly? 

 cherty and partly quartzitic in look, the bands being gray or brownish 

 black. Unfortunately I had no opportunity to see a typical outcrop, 

 since our field work lay chiefly on the Dwyka. 



The banded iron formation is widely found in Rhodesia and I had 

 an opportunity to study a fine outcrop on a kopje near Salisbury, where 

 the rock stands up as a sharp ridge overlooking the town, and plain. 

 No jasper occurs, but sandy looking or quartzitic silica is interbanded 

 with iron ore, the whole often greatly crushed and folded. The ma- 

 terial is exactly like the iron range rock of the Michipicoten region in 

 Ontario ; bnt the many loose blocks scattered over the hill give a very 

 different general impression fro-m the smoothly glaciated surface of such 

 ridges in Canada. The blocky character is no doubt due to splitting 

 by sudden changes of temperature between night and day in the dry 

 climate of the region. The enclosing rocks were hidden under debris, 

 but the nearest kopje is of granite, and the region, so far as seen by our 

 party, may be Archœan. 



A specimen of bright red banded jasper given me from northern 

 Ehodesia is closely like the so-called " jaspilite " of the Vermilion range 

 in Minnesota, but I have no information as to its geological sur- 

 roundings. 



1 Trans. Geol. Soc. S. Af., Vol. VII, Part II, 1904, p. 100; also ibid., Part 

 III. pp. 147 and 8. 



