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anticlinal Azoic basin beds belt border Brandywine Chester county Chester valley chloritic Clay creek Coatesville color conglomerate corner corundum crosses crystalline crystals Delaware county deposits Doe run Downingtown dyke east eastward edge exposures feet feldspar feldspathic formation fragments Frazer French creek furnace geological gneiss gneiss region gneissic gneissoid Goshen granite half a mile hornblendic hornblendic gneiss iron Kennett Square Lancaster county lime limestone lode London Grove lower magnesian Mesozoic mica mica-schists milk quartz mill mineral mines Nantmeal narrow nearly northern occurs Octoraro outcrop Pennsylvania Potsdam Potsdam sandstone Primal slates Prof quarry quartz quartzite quartzose railroad red sandstone ridge river road rocks Rogers sand sandstone schists Schuylkill serpentine side South Valley South Valley hill southern station stone strata structure surface syenite synclinal talc-mica thickness tion township trap trough upper Uwchlan Valley Forge Valley limestone vein west branch West Chester West Marlborough western westward white sandstone
Page i - Board of Commissioners of Geological Survey, In the office of the Librarian of Congress, at WASHINGTON, DC Electrotyped and printed by LANE S.
Page 197 - It would seem to be a pretty general fact, that such of these veins as are confined entirely or chiefly to the gneiss bear lead as their principal metal, whereas those which are included solely within the red shale are characterized by containing the ores of copper. But the zinc ores, viz: zinc-blende and calamine, prevail in greater or less proportions in both set of veins, existing, perhaps, in a rather larger relative amount in the copper-bearing lodes of the red shale.
Page 30 - Colonies in America, and to prevent the Erection of any Mill or other Engine for slitting or rolling of Iron, or any plating Forge to work with a Tilt Hammer, or any Furnace for making Steel in any of the said Colonies...
Page 197 - ... its average width at not less than eighteen inches. It is bounded by regular and well-defined, nearly parallel walls, the prevailing material of which is a coarse, soft granite, composed chiefly of white feldspar and quartz. " It would seem to be a pretty general fact that such of these veins as are confined entirely or...