. The copper-bearing rocks of lake Superior / by Roland Duer Irving. Geology; Geology; Copper ores; Copper ores. THE BEAVEE BAY GEOUP. 313 not products of infiltration like the so-called dendrites, since they run through and through the mass of the rock. They appear to me to furnish one more point of resemblance between the ancient felsites and quartz- porphyries and the modern rhyolites, and are another proof of the erup- tive origin of these rocks. Yet another proof of an eruptive origin is furnished by the rock of the. jifif Fig. 22.—Flowage structure in felsite, Minnesota coast. lower laye
. The copper-bearing rocks of lake Superior / by Roland Duer Irving. Geology; Geology; Copper ores; Copper ores. THE BEAVEE BAY GEOUP. 313 not products of infiltration like the so-called dendrites, since they run through and through the mass of the rock. They appear to me to furnish one more point of resemblance between the ancient felsites and quartz- porphyries and the modern rhyolites, and are another proof of the erup- tive origin of these rocks. Yet another proof of an eruptive origin is furnished by the rock of the. jifif Fig. 22.—Flowage structure in felsite, Minnesota coast. lower layers of this cliff. There are here large surfaces hundreds of feet square in which a fluidal structure may be seen on a large scale. Light- colored, pale-pinkish felsite and dark-brownish felsite are twisted together in various curling and snake-like forms; the mass as a whole dipping, as usual, 15° to the southeast. The contrast between the colors is very strong. The lighter material is the most abundant, and includes the darker. Fig. 22 represents an area of 20 by 28 inches. Some of the dark-colored bands are a foot or two in length and an inch to three inches in width, from which. 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 Irving, Roland Duer, 1847-1888. Washington, Govt. Print. Off.
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectgeology, bookyear1883
