of Veins. 359 4. Veins are filled only with fuch rocks as ap pear to have been in a ftate of complete fufion; as granite, porphyry, or trap. 5. Veins fometimes appear to terminate or clofe at their upper extremity or outgoing. 6. Mafies of rock fometimes appear infulated in the middle of veins, and confequently in fuch a fituation, as fhews that they could only,be fupport- ed by a ponderous fluid *. 7. Veins generally induce a degree of indura tion in the ftony ftrata or beds, or a burnt appear ance in the inflarpmable beds, through which they pafs t. 8. Mafies * “ The general fa&, of pieces of rock being found in fulated in veins, is certainly favourable to the notion of an inje&ed and ponderous fluid having originally fuftain- ed them.”—Playfair's llluf rations, p. 15 „. + “ Strata, whether fandy or argillaceous, where in contaft with the fides of veins of whinftone, are extreme ly hard and confolidated ; the former, in fome cafes, lofe their granulated texture, and are fometimes converted in to perfect jafper, “ As the beds of ftone, where they are in contadt with veins of whin, feem to acquire additional induration; fo thofe of coal, in like circumftances, are frequently found to have loft their fufibility, and to be reduced nearly to the condition of coke, or of charcoal. Few fa&s, in the hiftory of foffils, are more remarkable than this, and none more difedtly aflimilates the operations of the mine ral regions, with thofe that take place at the furface of the earth.”—Playfair’s Illujlrations, p. 73, 74. /