Note 12 — Chapter V · GALAPAGOS ARCHIPELAGO.

I believe that this case actually occurs in the Azores, where Dr. Webster (“Description,” p. 185) has described a basin-formed, little island, composed of strata of tuff, dipping inwards and bounded externally by steep sea-worn cliffs. Dr. Daubeny supposes (on Volcanoes, p. 266), that this cavity must have been formed by a circular subsidence. It appears to me far more probable, that we here have strata which were originally deposited within the hollow of a crater, of which the exterior walls have since been removed by the sea.