GALAPAGOS ARCHIPELAGO.
Chatham Island.--Craters composed of a peculiar kind of tuff.--Small basaltic craters, with hollows at their bases.--Albemarle Island; fluid lavas, their composition.--Craters of tuff; inclination of their exterior diverging strata, and structure of their interior converging strata.--James Island, segment of a small basaltic crater; fluidity and composition of its lava-streams, and of its ejected fragments.--Concluding remarks on the craters of tuff, and on the breached condition of their southern sides.--Mineralogical composition of the rocks of the archipelago.--Elevation of the land.--Direction of the fissures of eruption.