24 GEOLOGY OF MOOSE RIVER GOLD DISTRICT — WOODMAN. 



PART I.— STRUCTURE. 

 DATA FOR STRUCTURAL INTERPRETATION. 



Absence of fossils. — No fossil remains of any description 

 have been discovered in the rocks of Moose River. The only 

 appearances suggestive of them are some concretions which pro- 

 trude from the surface of a quartzite ledge on area 132, block 1. 

 These have weathered less than the rest of the rock, through 

 the possession of a firmer cement. They appear as ovoid pro- 

 jections ranging up to three inches in length, two in width and 

 three-quarters in height. Frequently stratification bands can 

 be seen to pass through them, but these are faint. The weather- 

 ing has left the surface of the concretions rough. 



In the slide they show no trace of organic origin. Their 

 appearance differs little from that of the other quartzites of the 

 district, except in a slightly coarser texture and more abundant 

 cement ; characteristics which decrease outward from a center, 

 and doubtless the concretionary growth is a function of them. 

 Two thin sections show grains of quartz cemented by silica and 

 calcite, with the usual secondary minerals, described later. The 

 grains are so situated as to leave no room for an organic nucleus, 

 now perhaps lost, but both specimens show an inorganic nucleus. 

 The cementation has centered around a few coarse grains of 

 sand, about twice the diameter of the other grains. In the 

 vicinity of these is a comparatively dense network of secondary 

 minerals, chiefly dark ones such as chlorite, biotite, and particu- 

 larly a dense amorphous iron oxide. Wherever the grains of 

 quartz are unusually large, there is a tendency to this increased 

 density ; but it centers chiefly around one spot. 



Lithological horizons. — Of rock horizons, only one can be 

 found which, by reason of its distinctness and continuity, might 

 be used throughout the region as a datum plane. This is the 

 slate belt containing the Jo. Taylor belt of leads. Unfortunately 

 the structure is such that this one is not visibly repeated across 



