. The copper-bearing rocks of lake Superior / by Roland Duer Irving. Geology; Geology; Copper ores; Copper ores. 326 COPPER-BEARING ROCKS OF LAKE SUPERIOR. high. The whole appearance at this place reminds one strongly of the alternations at the upper falls of the Montreal, on the South Shore/ save that the beds are thinner on Temperance River than on the Montreal. The peculiar ii'regularities to which these eruptive rocks are subject were well seen in a cliff side below Temperance River, where -10- Fig. 28 was drawn. The ashbed-diabases of this group are only met with at low horizons, being fo
. The copper-bearing rocks of lake Superior / by Roland Duer Irving. Geology; Geology; Copper ores; Copper ores. 326 COPPER-BEARING ROCKS OF LAKE SUPERIOR. high. The whole appearance at this place reminds one strongly of the alternations at the upper falls of the Montreal, on the South Shore/ save that the beds are thinner on Temperance River than on the Montreal. The peculiar ii'regularities to which these eruptive rocks are subject were well seen in a cliff side below Temperance River, where -10- Fig. 28 was drawn. The ashbed-diabases of this group are only met with at low horizons, being found on the coast not far below Baptism River, and again at Grand Ma- rais. Immediately overlying the quai-tzose-porphyry of the Beaver Bay Group, C of Fig. 23, is found the succession indicated in the following dia- Fig. 28.—Sectkm on Minnesota Coast, near Temperance gram (Fig. 29), in wHch the EiTsr The columnar portions are the lower massiyepor-j^^gg^ .^^ j^ ^ 1^^,^^^ ^^^_ lions of the flows; the dotted parts the amygdaloids or -i ' jr vesicuiar npper portions of the flows. nitic diabase - porphyrite, with conchoidal fracture, and containing per cent, of silica. The next is a black, medium-grained olivine-diabase or melaphyr, containing per cent, of silica, with the olivine wholly altered to a green and brown substance, and furnished above with an amygdaloid, and the uppermost. 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
