. Bulletin of the Geological Society of America. Geology. Mills • xxxyxxxxx/xxxxxxx • ? *\'>I? SVXVXXXXXX X X XXXXXX. Narragansett series Labradorite porphyry dike KX<- Riebeckite granite with porphy ritic marginal facies yj Ashton schist ^V- Grants Mills granite Cumberland quartzite Figure 3.—Geological Section through Cumberland Hill See BB on map, page 437 larger ones are of great length. While these have a very distinct trend parallel to the longer axis of the hill, they may be found running in all directions and, with innumerable ones of smaller size, form a most intri- cate and ama
. Bulletin of the Geological Society of America. Geology. Mills • xxxyxxxxx/xxxxxxx • ? *\'>I? SVXVXXXXXX X X XXXXXX. Narragansett series Labradorite porphyry dike KX<- Riebeckite granite with porphy ritic marginal facies yj Ashton schist ^V- Grants Mills granite Cumberland quartzite Figure 3.—Geological Section through Cumberland Hill See BB on map, page 437 larger ones are of great length. While these have a very distinct trend parallel to the longer axis of the hill, they may be found running in all directions and, with innumerable ones of smaller size, form a most intri- cate and amazing network of veins. Their directions seem to have been determined by the jointing and fracturing of the rock. The quartz is chiefly of the milk-white variety. In the veins, the crys- tals grow perpendicularly to the walls, giving rise to comb structures and very often with central vugs. In these the crystals are beautifully termi- nated and, as the rock commonly breaks along the line of these vugs, natural surfaces are covered with a mass of small quartz crystals which glisten like diamonds in the sunlight—a phenomenon that has given the hill its appropriate, though to the non-mineralogical mind a misleading, name. There are often successive layers of crystals separated at times by 42 Unpublished thesis. Mass. Inst. Technology, Boston, Mass., May, Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Geological Society of America. [New York : The Society]
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