The Geology and Extinct Volcanos of Central FranceJ. Murray, 1858 - 258 Seiten |
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Seite v
... period . After my return to England , being for some time at Cambridge , I had the advantage of frequent intercourse with the late Professor E. D. Clarke , who was himself well acquainted with volcanic Italy , and Professor Sedgwick ...
... period . After my return to England , being for some time at Cambridge , I had the advantage of frequent intercourse with the late Professor E. D. Clarke , who was himself well acquainted with volcanic Italy , and Professor Sedgwick ...
Seite x
... periods of immeasurable duration , upon the surface of supra - marine land . * The edition of this Memoir printed in 1826 soon became exhausted . I was , however , unwilling to reprint it without previously revisiting the country of ...
... periods of immeasurable duration , upon the surface of supra - marine land . * The edition of this Memoir printed in 1826 soon became exhausted . I was , however , unwilling to reprint it without previously revisiting the country of ...
Seite 2
... period , occurring severally in Auvergne , the Forèz , the Cantal , and the Velay . The granite of this district varies much in character , often within very narrow limits passing into gneiss , and sometimes , especially on its southern ...
... period , occurring severally in Auvergne , the Forèz , the Cantal , and the Velay . The granite of this district varies much in character , often within very narrow limits passing into gneiss , and sometimes , especially on its southern ...
Seite 2
... period , occurring severally in Auvergne , the Forèz , the Cantal , and the Velay . The granite of this district varies much in character , often within very narrow limits passing into gneiss , and sometimes , especially on its southern ...
... period , occurring severally in Auvergne , the Forèz , the Cantal , and the Velay . The granite of this district varies much in character , often within very narrow limits passing into gneiss , and sometimes , especially on its southern ...
Seite 6
... period in the tertiary æra , by as many freshwater lakes . These have left the proofs of their former existence in sedimentary strata of clay , marl , limestone , and sandstone , fre- quently containing the remains of numerous species ...
... period in the tertiary æra , by as many freshwater lakes . These have left the proofs of their former existence in sedimentary strata of clay , marl , limestone , and sandstone , fre- quently containing the remains of numerous species ...
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Allier ancient appears Ardèche augite Auvergne basaltic lava base basin bed of basalt beneath breccia calcareous calcareous peperino Cantal cellular Central France chain of puys channel character Clermont clinkstone colour columnar compact composed conglomerate considerable contains covered crater crystals of augite current of lava deposits distance district domite dyke east elevation eruption evidently excavation feet felspar fissures flowed formed fragments freshwater formation geologists Gergovia gneiss gorge granitic platform Graveneire Haute Loire heights hill lacustrine lake lava lava-current Le Puy Limagne limestone marls mass matter Mezen miles Mont Dore Monts Dôme mountain neighbouring numerous observed occupied olivine Pariou peperino plain Plate plateau points Pomel prisms probably Puy de Dôme Ramond recent remarkable ridge rise river sandstone scoriæ seen side similar Sioule slope strata stream of lava substance summit surface tertiary thick tion trachyte tuff valley vast vent Vivarais volcanic cones
Beliebte Passagen
Seite 5 - History of Latin Christianity ; including that of the Popes to the Pontificate of Nicholas V.
Seite viii - I conceive to be the only legitimate path of geological inquiry, and begin by examining the laws of nature which are actually in force, we cannot but perceive that numerous physical phenomena are going on at this moment on the surface of the globe by which various changes are produced in its constitution and external character.
Seite 210 - The leading idea which is present in all our researches, and which accompanies every fresh observation, the sound which to the ear of the student of Nature seems continually echoed from every part of her works is — Time...
Seite 210 - The time that must be allowed for the production of effects of this magnitude, by causes evidently so slow in their operation, is indeed immense ; but surely it would be absurd to urge this as an argument against the adoption of an explanation so unavoidably forced upon us. The periods which to our narrow apprehension, and compared with our ephemeral existence, appear of incalculable duration, are in all probability but trifles in the calendar of nature.
Seite 178 - ... older date, there occur in this part of France a multitude of volcanic cones like those in Auvergne, produced, in all probability, each by a single eruption. These cones are much more dilapidated than the majority of those near Clermont, of which chain they appear to constitute the prolongation. ' They are so thickly sown along the axis of the granitic range that separates the Loire and Allierfrom Paulhaguet to Pradelle, as generally to touch each other by their bases, and form an almost continuous...
Seite 118 - ... dykes of the same rocks.* The opposite sides of each excavation generally offer corresponding sections, the same beds being visible at similar heights on both declivities, but varying occasionally in thickness. This is universally the case in all the narrower gorges near the base of the mountain, where the diminished slope caused the lavacurrents to increase in width as much as in length ; and in these situations the same bed or series of beds often extends over a surface of many square miles,...
Seite 51 - ... that last sent up. Now the variety of trachyte which composes the Puy de Dome and the neighbouring domitic puys, consisting almost wholly 'of felspar, and therefore possessing the lowest possible specific gravity, and at the same time a very rude and coarse grain and highly porous structure, is precisely that species of lava which we should expect a priori, to have possessed the minimum of fluidity when protruded into the air ; * * See Considerations on Volcanos, p.
Seite 216 - ... of quadrupeds, birds, and plants, Eocene, Miocene, and Pliocene, have followed in succession ; yet the region has preserved from first to last its geographical identity ; and we can still recall to our thoughts its external condition and physical structure, before these wonderful vicissitudes began, or while a part only of the whole had been completed.
Seite 61 - ... across their channel, must have given birth to a lake by their stagnation ; and would probably have ended, as in the other instance, by wearing away a passage parallel to their former one, had not the hill forming their western bank, not in this instance composed of granite, but of a soft alluvial tufa, yielded, at some distance up the stream, to the excessive pressure of the dammed-up waters.
Seite 207 - ... with the occasional flooding of parts of this valley and its tributary ravines by lavas emitted in the eruptive paroxysms of the volcanoes on the neighbouring heights. Even were it allowable to have recourse to vague and hypothetical conjectures, we can conceive no gradual and progressive excavating forces, other than those which are still in operation wherever rains, frosts, floods and atmospheric decomposition act upon the surface of the earth. To these agents then we must refer the effects...