ABSTRACT
Basaltic lavas — Numerous craters truncated on the same side — Singular structure of volcanic bombs — Aeriform explosions — Ejected granitic fragments — Trachytic rocks — Singular veins — Jasper, its manner of formation — Concretions in pumiceous tuff — Calcareous deposits and frondescent incrustations on the coast — Remarkable laminated beds, alternating with, and passing into obsidian — Origin of obsidian -Lamination of volcanic rocks.
