Second Porphyry Formation. 351 Hate, as already mentioned, does occur in veins, and in thefe repofitories,,it has the waved ftruc- ture, and alternates with beds of quartz, and ores of different kinds. It is therefore demonflrated, that the wavings in this rock have not been pro duced by a force a&ing from below on foftened mechanical depofites, but have been formed by cryflallifation, from a ftate of folution, and which folution, we infer from the general fjtrucfure of the globe, to have been aqueous. Note G.—(Par. 5. p. 137, 138.) Second Porphyry Formation. When defcribing the fecond porphyry forma tion, I ought to have mentioned, that when the formation is complete, befides fienite, there alfo oc curs primitive clayftone, and primitive conglome rate ; and the whole feries appears in the follow ing order, from the fundamental rock upwards. x. Primitive Conglomerate.—Compofed of angular fragments of different primitive rocks. This bed is of inconfiderable magnitude. 2. Primitive Clayjlone.—lt is fomewhat earthy in its lower part, but gradually becomes more compadt, and includes cryftals of felfpar, when it paffes into the fuperincumbent porphyry. 3. Porphyry.—This rock paffes into, and is co vered by . 4. Sienite,—Which forms the upper part of the depofition. Note, «