CONTENTS. X7 lations, and geographic diflribution.—5. Chalk for mation : Its geognoftic characters and relations, and geographic diflribution.—6. Flcetz-trap formation.— 7. Coal formation : I. There are' three principal coal formations. Particular account of the geognoftic cha- rafters and relations, and geographic diflribution, of the independent coal formation.—8. Newef fleets-trap formation : Its geognoftic characters and relations, and geographic diflribution. CHAP. IX. Class IV.—Alluvial Rocks ; Avfgefchevunte-ge- birge, Werner, - - - Page 206 1. Definition: 2. Situation: 3. Divifion into two claffes: ijl clafs, Alluvial depofitions in mountainous coun tries : id clafs, Alluvial depofitions in low and flat countries. CHAP. X. Class V.—Volcanic Rocks; Vulcanifche-gebirge, Werner, 1 - . _ - 211 1. Pfeudo-volcanic rocks: 2. True volcanic rocks.— Pfeudo-volcanoes : 1. Defcription : 2. Geognoftic fitua- tion : 3. Geographic fituation : 4. Their effefts incon- fiderable—7rue volcanoes: 1. Their fhape : 2. Ap pearance when in a ftate of a&ivity : 3. and 4. Particu lar account of the phenomena prefented by volcanoes when in a ftate of activity: 5. Number of aftive vol canoes on the face of the earth : 6. Theories of volca noes ; that of Werner the mod plaulible. CHAP.