Plate VII.— THE KOXA DOLOMITE. 



Fig. 1. Weathered surface of Koua dolomite from Morgan Furnace. The background is the ordinary 

 granular gray dolomite. The rough protruding layers are chert, a portion of which is iron 

 stained. Natural size. 



Fig. 2. Brecciated chert at the hase of the Koua dolomite on the east side of sec. 13, T. 47 N., R. 26 W 

 (Atlas Sheet XXXIV). At the bottom of the Kona dolomite chert was concentrated so as to 

 make a layer 2 or 3 feet in thickness. Subsequent movement broke this layer into a breccia 

 which in some places closely resembles a conglomerate. The broken fragments are cemented 

 by later infiltrated quartz and by specular hematite and magnetite. The chert in places is 

 iron-stained, either by limonite or by hematite. Natural size. 

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