. Annual report. New York State Museum; Science; Science. GEOLOGY OF THOUSAND ISLANDS REGION 177 reversed in the two. Calculation of its norm gives the following result: Or ... Class 1, persalane Ab ... An ... ^95-29 Order 4, britannare Co ... • Qz ... Rang 2, toscanase Iiy ... 11 & Mt ... . I 4-44 Subrang 3, toscanose The rock of analysis 5 was not the normal acid granite gneiss of the locality where it was collected,, but somewhat darker colored, more basic in appearance, and the field relations definitely suggested that it had soaked up some amphi
. Annual report. New York State Museum; Science; Science. GEOLOGY OF THOUSAND ISLANDS REGION 177 reversed in the two. Calculation of its norm gives the following result: Or ... Class 1, persalane Ab ... An ... ^95-29 Order 4, britannare Co ... • Qz ... Rang 2, toscanase Iiy ... 11 & Mt ... . I 4-44 Subrang 3, toscanose The rock of analysis 5 was not the normal acid granite gneiss of the locality where it was collected,, but somewhat darker colored, more basic in appearance, and the field relations definitely suggested that it had soaked up some amphibolite. Nevertheless the analysis shows that this contamination is in slight amount, and the rock is to be classified in the same group as its predecessor, as its calcu- lated norm shows. Or .. Ab .. An .. Co .. Qz .. Hy .. II & Mt .. 93-85 5-49 Class 1, persalane Order 4, britannare Rang 2, toscanase Subrang 3, toscanose The mode of these rocks differs so little from the norm that it is not thought worth while to present the calculation. Both rocks con- sist chiefly of feldspars and quartz, with biotite as the principal additional mineral, a little magnetite, and trifling amounts of apatite, zircon, titanite, muscovite and pyrite. These minerals taken to- gether only amount to about 6fe in the first case and 8# in the second. In each case the surplus of alumina in the norm, calculated as corundum, is in just the proper amount to combine with the magnesia to form biotite. Bleached granite The rock of analysis 1 is from the margin of a small granite boss-cutting limestone, north of Redwood, which we regard as being of Laurentian age, and is a fresh sample of granite whitened by adjacent limestone. It is a somewhat more acid rock than the preceding. Unfortunately no samples which seemed satisfactory. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrat
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectscience, bookyear1902
