Elements of geology, or, The Elements of geology, or, The ancient changes of the earth and its inhabitants as illustrated by geological monuments elementsofgeolog00lyel Year: 1868 714 GRANITE IN VEINS. [Ch. XXXIII. It is here remarked, that the schist and granite, as they approach, seem to exercise a reciprocal influence on each other, for both un- dergo a modification of mineral character. The granite, still remain- ing unstratified, becomes charged with green particles; and the talcose gneiss assumes a granitiform structure without losing its strati- fication.* Professor Keilhau drew my att
Elements of geology, or, The Elements of geology, or, The ancient changes of the earth and its inhabitants as illustrated by geological monuments elementsofgeolog00lyel Year: 1868 714 GRANITE IN VEINS. [Ch. XXXIII. It is here remarked, that the schist and granite, as they approach, seem to exercise a reciprocal influence on each other, for both un- dergo a modification of mineral character. The granite, still remain- ing unstratified, becomes charged with green particles; and the talcose gneiss assumes a granitiform structure without losing its strati- fication.* Professor Keilhau drew my attention to several localities in the country near Christiania, where the mineral character of gneiss ap- pears to have been affected by a granite of much newer origin, for some distance from the point of contact. The gneiss, without losing its laminated structure, seems to have become charged with a larger quantity of felspar, and that of a redder color, than the felspar usu- ally belonging to the gneiss of Norway. Granite, syenite, and those porphyries which have a granitiform structure, in short all plutonic rocks, are frequently observed to con- tain metals, at or near their junction with stratified formations. On the other hand, the veins which traverse stratified rocks are, as a general law, more metalliferous near such junctions than in other positions. Hence it has been inferred that these metals may have been spread in a gaseous form through' the fused mass, and that the contact of another rock, in a different state of temperature, or some- times the existence of rents in other rocks in the vicinity, may have caused the sublimation of the There are many instances, as at Markerud, near Christiania, in Nor- way, where the strike of the beds has not been deranged throughout a large area by the intrusion of granite, both in large masses and in veins. This fact is considered by some geologists to militate against the theory of the forcible injection of granite in a f
Size: 1897px × 1054px
Photo credit: © Bookworm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: archive, book, drawing, historical, history, illustration, image, page, picture, print, reference, vintage
