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/ Veins. 237 above or below, but is, as it were, a fecretion from the rock itfelf. Such veins are denominated cotem- * poraneous, becaufe they appear to have been formed almoft at the fame time with the rock in which they occur. In the ifland of Arran there are nume rous interefting cotemporaneous veins, in granite, gneifs, mica-flate, clay fl.ite, and greenftone, as at the Tor-nid-neon, Glen-Rofa, Loch-Ranza, Glen-Clachan, Glen-Duig, & c . of which I intend to publifli a particular defcription. c. Veins fometimes crofs each other, without caufing any change of diredion ; but more fre quently we find the diredion confiderably changed. d. When veins meet under an acute angle, the newer frequently traverfes the older j runs paral- lei with it to a confiderable extent, on its lower fide, and then again diverges under the fame an gle it eroded it ; fometimes the newer vein does not fully traverfe the older, but changes its direc tion 111 the middle ; runs through the body of the vein ; and after a longer or fliorter courfe, again diverges at the fame angle it entered. Sometimes the newer vein does not even traverfe the older; only meets it ; then runs parallel with it; again diverges; and this is fometimes frequently re peated in the courfe of the vein *. Sometimes * It is an incontrovertible fad, that no veins of the fub- flance of a fubjac^nt rock ever {hoot into a fuperincutn. bent one 1 ; becaufe the itrudme of the cruit of the gl 0D e[ from
