foot or more, traversing a series of sedimentary beds of mica 

 schists and limes, high in calcium carbonate content, which 

 constitute the country rock of the region round about Wins- 

 low for many square miles. These sedimentary shales and 

 schists, originally, of course laid down in approximately 

 horizontal layers were, during the mountain building period 

 of their geologic life, tilted up on edge, until they now stand 

 nearly vertical. 



Following this upheaval they were intruded by two ser- 

 ies of younger rocks — namely, first the tin bearing veins 

 which follow very nearly the general course of tlie stratifi- 

 cation of the sedimentaries, though occassionally cutting 

 sharply across them; and, secondly, massive igneous dikes 

 closely paralleling the strike of the veins, and possibly in- 

 timately connected genetically with the tin veins. These 

 dikes are called in Cornwall, the oldest tin mining region of 

 which we have contemporaneous knowledge, 'Elvans' and are 

 regarded by Cornish miners and mining geologists as indis- 

 pensable and infallible companions and guides to true tin- 

 bearing veins. It is rudimentary knowledge in Cornwall 

 that if these 'Elvans' and the tin-bearing veins meet or cross 

 or intersect one another in their course across the country 

 or in the dip beneath the surface, enormously enhanced rich- 

 ness of metal content either in tin, tungsten or silver, may 

 be confidently predicted. Such elvans occur in close proxi- 

 mity to the Winslow veins on which the hundred foot shaft 

 was sunk. 



In the course of exploratory work on this deposit which 

 I have been conducting for the past three years, I have traced 

 the principal elvan or dike from a farm in Sidney at a point 

 several miles south of the tin deposit and on the opposite 

 bank of the Kennebec River, northeastward till it plunges 

 beneath the water on the Sidney shore, crosses the river 

 and emerges on the Winslow shore, continuing straight on 

 until it crosses Drummond Brook within a few feet of the 

 tin veins and the old shaft. Thence it runs northeast to a 

 point on the east bank of the Kennebec just below the Win- 

 slow end of the Waterville bridge, from which it may be 

 plainly viewed by any passerby. 



Reference has been made to the significance attached 

 by Cornish miners and mining geologists to the "Elvans" 

 or dikes of trappean rocks, paralleling the tin veins in that 

 region, famous during so many centuries as the world's 

 greatest centre of tin mining. 



De la Beche, the greatest authority on the geology of Cor- 

 nish tin deposits, lays especial stress on their importance. 



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