170 THE VERMILION IRON-BEARING DISTRICT. 



The following description of an area on the portage between Wind and 

 Moose lakes makes clear the difficulty which one experiences in attempt- 

 ing to discriminate between these greenstones and some of the rocks that 

 are associated with and derived from them. The rock on the north side 

 of the high ridge overlooking Wind Lake is ixndoubtedly a green schist 

 derived from the Ely greenstone. It is broken by diagonal joints running 

 in two directions, lines bisecting the acute angles of the rhomboids formed 

 by the intersection of these joints being parallel to the strike. The minute 

 diagonal fractures have been largely cemented by some material, as is 

 shown by ridges that run along the weathered surfaces. The rock is veined 

 with white quartz, but there is no definite banding except that produced 

 by this material which has filled the fractures. There is no appearance 

 whatever of pebbles in the rock. The schistosity is A^ery strongly marked. 

 Along the schistosity there are numerous fine quartz veins and some 

 fractures filled by other materials, so that the rock shows a fairly distinct 

 banding parallel to the schistosity. 



South of this green schist there is a peculiar rock wnich shows very 

 fine banding along the schistosity, as does the green schist above described. 

 This banding does not seem to be due to secondary cementation, but appar- 

 ently results from the mashing of originally heterogeneous material. On 

 weathered surfaces of this rock that lie transverse to the schistosity there are 

 obscure roundish or elliptical spots having their long directions parallel 

 with the trend of the schistosity. These roundish spots are presumably 

 mashed pebbles. They are. very numerous, arid increase in distinctness as 

 one passes southward from the contact, and within a distance of 30 or 40 

 feet the rock assumes a distinctly conglomeratic appearance. When the 

 rock is split the pebble-like masses are seen to be greatly extended in 

 the direction of the schistosity. These masses are several times longer 

 in the direction of the dip than along the strike, and from two to ten times 

 as broad (along the strike) as they are thick. In these respects the rock 

 is identical with the remarkable schist conglomerates of Vermont described 

 by Hitchcock" in 1860. 



In the conglomeratic rock at Wind Lake the regular system of fractures 

 spoken of as occurring in the mass first described — the green schist adja- 

 cent to the conglomerate — are not present, at least with any such regularity, 



a Geology of Vermont, Vol. I, 1861, pp. 28-42. 



