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Show xxiv CONTENTS. PAGE France at successive periods-Mont Doran extinct volcano-Vclay-~lom.b du Cantal-Train of minor volcanos stretching from Auvergnc to the V1varms -Monts Domes-Puy de Comc-Puy Rouge-Ravines excavated through Java-Currents of Java at different heights-Subjacent alluviums of distinct ages-The more modern lavas of Central France may belong to the Miocene period-The integrity of the cone11 not i~:onsistent with ~his opinio~-~0 eruptions during the historical era-Divmon of volcanos mto ante-d1luvmn and post-diluvian inadmissible-Theories respecting the effects of the :Flood considered-Hypothesis of a partial flood-Of a universal deluge-Theory of Dr. Buckland as controverted by Dr. Fleming-Recapitulation 257 CHAPTER XX. Eocene formations, continued-Basin of the Cotentin, or Valognes-Rennes -Basin of Belgium, orthe Netherlands-Aix in Provence:-F?ssil insectsTertiary strata of Englanu-Basins of London and Hampshire-Different groups-Plastic clay and sand-London clay-Bagshot sand-}'resh-water strata of the Isle of Wight-Palreotherium and other fossil inammalia of Binstead-English Eocene strata conformable to chalk-Outliers on the t!Ievated parts of the chalk-Inferences drawn from their occurrence-Sketch of a theory of the origin of the English tertiary strata 275 CHAPTER XXI. Denudation of secondary strata during the deposition of the English Eocene formations-Valley of the Weald between theN orth and South Downs -Map-Secondary rocks of the Weald divisiple into five groups-North and South Downs-Section across the valley of the Weald-Anticlinal axisTrue scale of heights-Rise and denudation of the strata gradual-Chalk escarpments once sea-cliffs-Lower terrace of ' firestone,' how causedParallel ridges and valleys formed by harder and softer beds-No ruins of the chalk on the central district of the Weald-Explanation of this pheno· menon-Double system of valleys, the longitudinal and the transverseTransverse how formed-Gorges intersecting the chall<-Lewes Coomb- Transverse valley of the Adur 285 CHAPTER XXII. Denudation of the Valley of the ·weald, continued-The alternative of the proposition that the chalk of the North and South Downs were once continuous, considered-Dr. Buckland on the Valley of Kingsclere-Rise and denudation of secondary rocks grauuai-Concomitant deposition of tertiary strata gradual-Comllositiou of the latter such as would result from tho wreck of the secondary rocl,s-Valleys and furrows on the chalk how causeu CONTENTS, XXV PAGE -Auvergne, the Paris basin, and south-east of England one region of earth-quakes during the Eocene period-Why the central parts of the London and Hampshire basins rise nearly as high as the denudation of the ·wealdEffects of protruding force counteracted by the levelling operations of water -Thickness of masses removed from the central ridge of the Weald-Great escarpment of the chalk having a direction north-east and south-westCurved and vertical strata in the Isle of Wight-These were convulsed after the ueposition of the fresh-water beds of Headen Hill-Elevations of land posterior to the crag-Why no Eocene alluviums recognizable-Concluding remarks ou the intermittent operations of earthquakes in the south-east of England, and the gradual formation of valleys-Recapitulation 303 CHAPTER XXIII. Secondary formations-Brief enumeration of the principal groups-No species common to the secondary and tertiary rocks-Chasm between the Eocene and Maastricht beds-Duration of secondary periods-Former continents !'laced where it is now sea-Secondary fresh-water deposits why rare -Persistency of mineral composition why apparently greatest in older rocks -Supposed universality of red marl formations-Secondary rocks why more consolidated-Why more fractured and disturbed-Secondary volcanic rocks of many different ages 324 CHAPTER XXIV. On the relative antiquity of difft!rent mountain-chains-Theory of M. Elie de Beaumont-His opinions controverted-His method of proving that different chains were raised at distinct periods-His proof that others were contemporaneous-His reasoning why not conclusive-His doctrine of the parallelism of contemporaneous lines of elevation-Objections-Theory of parallelism at variance with geological phenomena as exhibited in Great Britain-Objections of Mr. Conybeare-How far anticlinal lines formed at the same period are parallel-Difficulties in the way of determining the relative age of mountains 337 CHAPTER XXV. On the rocks usually termed 'Primary '-Their relation to volcanic and sedimentary formations-The ' primary' class divisible into stratified and unstratified-Unstratified rocks called Plutonic-Granite veins-Their various forms and mineral composition-Proofs of their igneous origin-Granites of the same character produced at successive eras-Some of these newer than certain fossiliferous strata-Difficulty of determining the age of particular granites-Distinction between the volcanic and the plutonic rocks-Trappean rocks not separable from the volcanic-Passage from trap into graniteTheory of the origin of granite at every period from the earliest to the most rcct:nt 352 |