“Relation of what happened by the Will of God, on Saturday, the 10th of September, 1541, two hours after sunset in the town of Santiago de Guatimala.” Ternaux-Compans.
Historia Verdadera de la Conquista de la Nueva España escrita por el Capitan Bernal Diaz del Castillo, uno de sus Conquistadores.
The substances thrown out from craters frequently differ in their character. Judging from the composition of the surface of portions of the land near the Guatemala volcanoes, especially upon the slopes of the barrancas, it is evident that large quantities of pozzolana were ejected. One of the latest eruptions that has occurred was at the Island of Santorin in the Grecian Archipelago in February, 1866. I was present when the new volcano emerged from the sea.
The inhabitants of Santorin, upon seeing volumes of steam and smoke issuing from the waters of the bay, apprehended some serious peril to be imminent. They feared the possibility of their town being overwhelmed by an eruption of ashes, and made a request that a ship of war should be sent to the spot to render any assistance that might be necessary. I immediately went there in the “Racer” and remained until all fears of danger had passed away.
The crater of the volcano, afterwards called Aphroessa, rose slowly from the surface of the water, and it was possible to observe the nature of the interior during the intervals between the eruptions. There was no lava or pozzolana, but only large cinders which, as they issued from the crater, were thrown into the air, and then fell upon the outer slopes, thus gradually forming an island.
It was a very remarkable scene; during the day there were heavy volumes of smoke and constant rumbling sounds, as the pent up forces below the mouth of the crater were gathering strength to throw forth the mass of cinders that closed them in. At night the glare caused by the reflection of the fire of the interior upon the dense clouds immediately overhanging it was very vivid. The surface of the surrounding waters was over-spread by running tongues of brilliantly coloured flames. The island was composed of cinders and ashes, whose porous nature could never permit any lodgement of water upon them. I examined several of the craters of the extinct volcanoes on the islands adjacent to Aphroessa, and there was no instance of any small pond or collection of water existing within them. The interior of the Volcan de Agua, possibly contained a thick substratum of water-bearing pozzolana.
An account of the volcanoes of Santorin was given by Sir Charles Lyell. “Principles of Geology.” Vol. ii, pp. 70.