r$2 •’ FLCETZ ROCKS. 7. It occurs abundantly in the iflands of Arran and Lamlafh in the Frith of Clyde•, alfo in fmaller quantities in the upper part of Dumfrieslhire, and in the county of Selkirk. Braid Hills, and part of the Pentland Hills, near Edinburgh; the Girleton Hills at Haddington, and, according to my pupil Dr Ogilvy, North-Berwick Law, and Traprain or Dumpender Law, in the fame county, are compofed of this rock. I fufpedt that the por phyry of Cumberland, which probably occurs among tranlition mountains, is alfo porphyry-ilate. It occurs in great abundance in Bohemia ; alfo, but in lefs quantity, in Lufatia; in the Princi pality of Fulda ; in the Rhongebirge ; at Hohen- tuiel and Hogau in Upper Suabia; at Vicenza, in the Euganean Mountains; on the Pic de Teyde in Teneriffe ; and in great abundance in South America, as 1 fufpedl that much of the porphyry of Humboldt will prove to be porphyry-flate. 5. Trap-TufF. Trapp-Tuff.—Werner. 1. This rock was formerly denominated Bafalt- tuff j but as its bafis is not always bafalt, IVerner rightly names it Trap-tuff. 2. It is compofed of maffes of bafalt, amygdaloid, hornblende-rock, fandftone, and even pieces of wood, (as in the ifland of Canna), cemented to gether by a rather loofe fpongy clayey bafis, which has been formed from Uecompofed bafalt or wacke rock.
