(GEOLOGICAL EXPLORATIONS AND LITEKATUltE— 188L'. 95 



occurs ill large qua-uTity l)et\veeu tlic lenses and t'orins in nearly every 

 case the rock-bedding under the different lenses. * « * Jasper occurs 

 mostly on the toot-wall side of the lenses and l)ack of the chlorite-schist." 

 The author then, assuming that the ore was accumulated liy the transport- 

 mg and oxidizing action of water, proceeds to account for its deposition by 

 supposing the original drainage of the area to have luul an east-west 

 course through a numlier of small lakes. In these lakes precipitation of 

 limonite may have taken place, which, upon metaniorphism, was trans- 

 formed into hematite and magnetite. The ditferent lenses of ore may 

 represent the accumulations in different lake basins, or portions of the 

 accumulation in a single basin, in which the process of deposition was 

 interrupted at intervals. On this theory the overlapping of the lenses is 

 explained by slight shifting of the localities of deposition, lirought about 

 by the same causes as produced tlie suspension of de))ositioii. I'hc se([uence 

 of the deposits, viz, ore, quartzite, and slate, is tlu)Ught to be due to a sej)- 



Flo. 2.— Horizontal section of ori> bodies at the surface of tbe Champion mine. 



aration of the material in the lakes through the mechanical action of 

 wind-disturbed water. 



Professor Munroe, in referring to this theory of Payne's, calls attention 

 to the fact that the water of a lake, disturbeil by the action of the wind, 

 would not separate a mixture of substances into its component ])ortions. 



The deposit formed iu the bottom of a hike would be no riclier, on the average, 

 than the sediment flowing in. There might be local patches of concentration, due to 

 wave action on the shores of the lake, or to the deposition of heavy sediment at the 

 mouths of small streams, but the deposit would be like the immense beds of "mixed 

 ore" found in the iron regions. * * * 



Munroe believes, however, that the mechanical action of water has in 

 some cases played an important part in the concentration and purification 

 of the rich ores, but he believes that the water was in the form of running 

 streams. The heavy and purest ores were concentrated above the lighter 

 and less pui-e ones, which were carried farther downstream, wliile the 



