Newest Fixetz-Trap Formation. 197 faw it forming a ftream in countries containing extind volcanoes. 6. Compad Felfpar. Dichter Felfpath.—Werner. 1. This rock probably occurs in confiderablc beds; or even mountain maffes, in this formation. 2. The Pentland Hills, near Edinburgh, afford good examples of this rock. 7. Clayftone. Thonftein.—Werner. 1. This rock accompanies the compad felfpar, and appears to pafs into it. 2. The Pentland Hills afford examples of this rock. 8. Gravel, Sand, and Clay. Thefe frequently occur together. The gravel ufually occupies nearly the loweft part of the for mation, and by the diminution of the magnitudes of its grains, paffes into fand. The grains of fand alfo become fmaller in its upper beds: laftly, it becomes clayey, and at length paffes into clay. The clay paffes into wacke ; the wacke into bafalt; the bafalt into greenftone, and this latter into grey- ftope and porphyry-flate. Beds of fhells, &c. fome- times