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Meanwhile the second vent continued active, and, piling up more and more matter round the central crater, surmounted the former vent, and covered its ejecta with newer sheets of lava, ashes, and lapilli, while numerous smaller vents, scattered all over the sides of the mountain, gave rise to smaller cones and craters. Fourth Stage.
The district around the Laacher See is covered by laminated ejecta of the old volcano, probably of subaërial origin, through which bosses of the fundamental slate peer up at intervals, while the surface is diversified by several truncated cones.
If this be so, then we possess a key by which to determine the period of the first formation of volcanoes in Central France; for, as the animal remains enclosed in the lacustrine deposits of the Vale of Clermont belong to the early Miocene stage, and the earliest traces of contemporaneous volcanic ejecta are found only in the uppermost deposits, we may conclude that the first outburst of volcanic action occurred towards the close of the Miocene period a period remarkable for similar exhibitions of internal igneous action in other parts of the world.
During a pause in volcanic activity, beds of limestone with marine shells were deposited. Second Stage. This sea-bed was gradually upraised into the air, while fresh sheets of lava and other ejecta were accumulated round the vents of eruption, of which there were two principal ones the older under the present Val del Bove, the newer under the summit of the principal cone.
To this custom of transferring the Ludi Appollinares to another place where the Tyber had overflowed the Circus Maximus, Ovid alludes in his Fasti. Altera gramineo spectabis equiriacampo Quem Tiberis curvis in latus urget aquis, Qui tamen ejecta si forte tenebitur unda, Coelius accipiet pulverulentus equos.
Accompanying the lava-streams are great beds of volcanic agglomerate, which Mr. Scrope considers to have been formed contemporaneously with the lava which they envelop, and to be due to torrents of water tumultuously descending the sides of the volcano at periods of eruption, and bearing down immense volumes of its fragmental ejecta in company with its lava-streams.
In the first of the six above-mentioned scenes, which is a round, is Guido Farnese, with many persons, all well executed, about him, and with this inscription below: GUIDO FARNESIUS, URBIS VETERIS PRINCIPATUM CIVIBUS IPSIS DEFERENTIBUS ADEPTUS, LABORANTI INTESTINIS DISCORDIIS CIVITATI, SEDITIOSA FACTIONE EJECTA, PACEM ET TRANQUILLITATEM RESTITUIT, ANNO 1323.
I have frequently described elsewhere with considerable detail the telescopic appearance of these features under various phases, and have pointed out that though large apertures and high powers are needed to see these cones to advantage, the dusky areas, easily traced on photograms, might be usefully studied by observers with smaller instruments, as if they represent the ejecta from the crater-cones which stand upon them, changes in their form and extent could very possibly be detected.
Such presence or absence does not of course affect the essential chemical composition of the ejecta, but it materially influences the form in which the matter is erupted. The agency of water in volcanic eruptions is a very interesting and important subject in connection with the history of volcanic action, and has been ably treated by Professor Prestwich.
The disgusting habit of eating human excrement is mentioned by Schurig, who gives numerous examples in epileptics, maniacs, chlorotic young women, pregnant women, children who have soiled their beds and, dreading detection, have swallowed their ejecta, and finally among men and women with abnormal appetites.
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