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Stratigraphical geology and palaeontology Manual of geology
- Titel
- Stratigraphical geology and palaeontology
- Autor
- Etheridge, Robert
- Erscheinungsort
- London
- Bandzählung
- 2
- Erscheinungsdatum
- 1885
- Umfang
- XXIV, 712 S.
- Sprache
- English
- Signatur
- VII 1596 8. (2)
- Vorlage
- Universitätsbibliothek Freiberg
- Digitalisat
- Universitätsbibliothek Freiberg
- Digitalisat
- SLUB Dresden
- Lizenz-/Rechtehinweis
- Public Domain Mark 1.0
- URN
- urn:nbn:de:bsz:14-db-id5121650763
- PURL
- http://digital.slub-dresden.de/id512165076
- OAI-Identifier
- oai:de:slub-dresden:db:id-512165076
- SLUB-Katalog (PPN)
- 512165076
- Sammlungen
- Bestände der Universitätsbibliothek Freiberg
- LDP: UB Freiberg Druckschriften
- Strukturtyp
- Band
- Parlamentsperiode
- -
- Wahlperiode
- -
- Titel
- Part III.—Upper Palæozoic Strata
- Digitalisat
- SLUB Dresden
- Strukturtyp
- Kapitel
- Parlamentsperiode
- -
- Wahlperiode
- -
Inhaltsverzeichnis
- Mehrbändiges WerkManual of geology
- BandStratigraphical geology and palaeontology -
- EinbandEinband -
- AbbildungGeological Map Of The British Islands -
- TitelblattTitelblatt III
- KapitelPreface V
- InhaltsverzeichnisSynopsis Of Contents VII
- RegisterTabular Summaries XIX
- RegisterList Of Plates XXIII
- KapitelIntroduction 1
- Kapitel[Part I.—Lower Palæozoic Strata] 2
- KapitelPart II.—Middle Palæozoic Strata 151
- KapitelPart III.—Upper Palæozoic Strata 212
- KapitelPart IV.—Dyas 306
- KapitelPart V.—Triassic Rocks [Mesozoic Or Secondary] 325
- KapitelPart VI.—Jurassic Or Oolitic Period 348
- KapitelPart VII.—Upper Mesozoic Strata 512
- KapitelPart VIII.—Canozoic Or Tertiary Period 598
- RegisterCorrigenda Et Errata 692
- RegisterIndex 693
- EinbandEinband -
- BandStratigraphical geology and palaeontology -
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GROWTH OF THE COAL FLORA. 267 Comparative Value of Different Floras.—The following analysis will tend to show the values of the respective floras in Britain, and she comparative prevalence of coal in the different series, although the number of species does not in any way determine the value of the flora as contributing to the formation of coal:— British Tertiary strata have yielded 167 genera and 348 species. 1 „ Cretaceous „ „ 15 „ 28 „ „ Purbeck and Wealden 27 „ 39 „ „ Jurassic strata „ 64 „ 191 „ „ Triassic „ „ 9 „ 12 „ „ Permian „ „ 18 „ 26 „ „ Carboniferous „ 75 „ 328 „ „ Devonian „ „ 18 „ 27 There can be little doubt that much, if not all, coal results from the decomposition and transformation of the flora upon the site of its growth. This is strongly evidenced by the usual occurrence of a bed of clay under the coal, containing the roots of plants. This clay repre sents the root bed, which contained the roots of the overgrowing plants, and, therefore, the old soil, occurring below every coal-seam. In York shire, the siliceous rock, called “ Ganister,” occurring in similar positions, shows that the coal-plants grew upon arenaceous or sandy soils. Conditions favourable to Coal Growth.—The conditions favour able to the production of coal seem, therefore, to have been forest growth in swampy ground, and in estuaries about the mouths of great rivers—oscillations of level governing the rate of accumulative de position, and the pauses between depression (or stationary periods) being of sufficient duration to allow of the growth and decay of plant life, so as to form a seam of coal. The thickness, again, would seem to have been dependent upon the time and conditions allowed by the downward land-movements, which brought in new layers of sedimen tary matter through river-delta action, either marine or brackish,—• the sediment thus intermittently thrown down forming, on re-eleva tion, the soil for fresh growth. We expect, therefore, to find coal or coaly deposits wherever strata of estuarine origin are developed in considerable mass; and this is the case all through the upper Car boniferous series, the Jurassic (as finely shown in the estuarine coals of the Inferior oolite shales and sandstones of Yorkshire), and in some foreign Cretaceous rocks. All these three are coal-bearing horizons, but in very unequal degrees, abnormality being the condition of the two latter, as compared with the highly developed and true coal- measures of the Carboniferous period, or coal-measures proper. The Paleeozoic coal-measures are mainly confined to countries north of the equator, especially those of the American and European continents. 2 Mesozoic coals are more abundant in the Southern Hemisphere ; 1 Both genera and species will be increased from this horizon chiefly through research in the middle Eocene strata. 2 The vast and depressed area of the Pacific—if we argne from the presence of the carboniferous rocks of Australia, &c.—may contain regions of Palaeozoic strata, and amongst them greatly extended carboniferous rocks. The older rocks of New Zealand, Van Diemen’s Land, New South Wales, and Australia, clearly show how extended they must be in the South and Indo-Pacific regions.
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