Page:Encyclopædia Britannica, Ninth Edition, v. 10.djvu/364

Rh 350 Among the more frequent species are An(lu°m‘om_r/a mocliolaris, Jiitliracos-ia orulis, A. -r0bu.s-ta, -l. arutu, -lnthracoplr'ra I-'1'ou'm'aua, Arieitlopcetcn _pap_i/merits, and (:'onz'a[itcs 1.i'stcri'. But at the top -if the Middle Coal-nieasurcs, near lllancliestcr, a band of true inarine shells occurs, including Clcnodonta, .'auti'1us, Disei'tcs, (}'om'ali'tcs, and Orthoccras. The little Spi/'0rbz's curboiim'[us abounds in some shales. The crustaceans are chiefly represented by 1}c_i/I'1'cIu'a and Eslhcria, but large ctiryptci'id forms likewise occur. Fishes occur fre-pietitly, remains of the larger kinds usually appearing as scales, teeth, tin-spines, or bones, while the smaller gaiioids are often preserved cntire. Coininon species are illcgaliclatliys 11i'bbcrtz'(?), 1.’lcz':o.ius granulatus, "u:Iacanlhus lcpturus, .P¢cIcL'oiu'scus Egcrtoni, ]’lcitrm.-unthus _(/z'bbu.sus. The British C‘arboiiiferous rocks have yielded 13 genera of labyrinthodonts (xl7lf}l1'(lc08(lll7'ltS, LoJ:0-mma, Uplddrrrpclon, Pholidcrpclon, Plcroplarr, l'rocora'_i/Ins, &c.). These were probably tluviatile animals of predaccous habits, living on fish, crustacea, and other organisms of the ficsh or salt waters of the coal lagoons. The larger forms are believed to have measured 7 or 8 feet in length; some of the smaller e.:aniple.;, though adult and perfect, do not exceed as many inches.‘ That the woods of the Cai'bonifcrous period were not devoid of insect life is known from the discovery of some beetles and neuroptera at Coalbrookdale. CONTINENTAL Eer.oI>n.—As in Britain so on the Con- tinent the Carboniferous system occupies many detached areas or b.1sins~—the result partly of original deposition, partly of denudation, and partly of the spread and overlap of more recent formations. There can be no doubt that the English Carboniferous Limestone once extended con- tinuously eastwar.l across the north of France, along the base of the Ardennes, through Belgium, and across the present valley of the Rhine into Vestphalia. From the western headlaiids of Ireland this calcareous formation can thus be traced eastward for a distance of 750 English miles into the heart of Europe. It then begins to pass into a series of shalcs and sandstones, which no doubt represent the same proximity to shore as the similar strata in the north of England and Scotland. In Silesia, and still much further eastwards in central and southern Russia, representatives of the Carboniferous Limestone appear, but interstratified, as in Scotland, with coal—bearing strata. Traces of the same blending of marine and terrestrial eoii- ditions are found also in the north of Spain. But over central France, and eastwards through Bohemia and Moravia into the region of the Carpathians, the Coalnieasures rest directly upon the older formations, most commonly upon gueiss and other crystalline rocks. It would appear that these tracts had remained above water during the time of the Carboniferous Limestone, but were gradually depressed during that of the Coal-measures. In the north of France and Belgium the British type of the Carboniferous system is well shown. At the base lies a group of green, grey, and reddish sliales and yellow sandstones, precisely similar in lithologieal character to parts of the Caleii'ei'o1is Sand- stones of Seotlan.l. They are well seen in some recent r-ailway cuttings to the north of Boulogne, and also in the valley of the Meuse above Namur, lying upon. the Psaniniites de Condroz or Upper Devonian beds. They are succeeded by the Carboniferous Limestone, which is subdivided into eight formations, having an aggregate thickness of 800 metres, and each characterized by its own assemblage of fossils. The horizon of the Millstone Grit is marked by the oceurrence of certain alum-scliists. The Coal- incasures of this area have been referred to in the article CAL.2 The Saarbruek coal-ﬁeld furnishes a good example of that type of the Carboniferous system where the lower marine series is absent. It lies uneonforniably on Devonian rocks, and attains a thickness 1 Miall, lirit. Assoc. Rep, 1873, p. 246. 2 [In the article Cou., vol. vi. p. .36, the coal basin of llardingheni is said to be of Carboniferous Limestone age. This, which t'lpp(‘dX‘(:(l to be the most probable view of a very obscure point. has been proved to be it mistake, as the strata are actually (.‘oal-measures inverted in po.si'ion. the same disturbance being elini'aetei'istie of the s )lll.h side of the basin of the l’as-dc-Calais tor a consiclernblc di~tance. This is now so generally recognized that boiings for coal in that basin through the Ter- tiar_v an 1 Cl'CtIl(‘C')llS formations are not necessarily stopped on re iehing Devonian strain. as coal-seams have been discovered vertically below the older strata at covisidcrzible depths. e.g., at Anchy nu liois. In another pit. at jCourribres, the fact that the measures on the upper levels are inverted in position has been recently proved by the sinkings traversing the same seams in reverse ord -r, i.c.. in their normal position in the lower workintzs. These facts have an important bearing on the qin-stion of the probable extension of the (‘oal-mctisnres in the soutli-cast of Enizlanrl. The discovery (in 1878) of l)cvoni:in strain. at the moderate dr-ptli of HO’! feet in the centre of London, at .lessi's 3leiix's brewery. is another interesting fact that bears out the views previously 1-ut forivunt by _li' Godwin Austen. (ll. 15.)] GEOLOGY [vi. STRA'l‘IGR.~‘lI“IllCAL. of nioi'e than 10,000 feet. of strata :— 2. Upper series, consisting at the top of red sandstones, below which come Sllillt'S, sandstones, &c., with a few coal-seani.~.— --'1n[liracosz'a, Eslhcriu. 1. Lower series, consisting ofan upper group ofred eongloinerates, saiidstoiics, clays, resting upon the great coal-bi-nring division. .-bundant plants, with labyrinthodonts and inset t rcinain:_:. Geinitz, drawing attention to the distribution of plants in the Saxon Coal-nicasurcs, reniarlts that a certain order can be obsei-v<-cl in their appearance. lle divides the strata at-t-ui'<liiigl_v into llll't:t: zones, each marked by a cliai-actci'istie ass:-inlnlage of plants, and he bclieves that the classification can be applied in other t'Ulllll.‘.‘lt‘.~'-. 3. The Fern Zone, marked by the profusion of its ferns l_S'/i/z-'u0p- tcrfs, I13/iiicizoplig/(lites, ScIu7:opter[.~', Utlvllfuplv ri.»-, _'. uru,"rn'-, t'ycIop[cri's, Alcthoptcris, Ctu(I0ptc7'z's). This is ninli-rlai-l l y 2. The Sigillaria Zone, containing many species of .S'i_:/I//uri I. also Lcpidodcmlron, (,'alamL'tcs, Astcrophyllilcs, and a lew l'- rn.~. 1. The Lycopod Zone, abounding in .S'agcmu'£¢¢- l7_i'(/u[..u'u n, with Sp/icnoptci'[s dils-tans, Cala-nu'tcs trmz.si'lz'oiii's, &c. The lowest of these zones (1) is compared by (icinitz with the Culin, that is, the sandy, slialy, and coal-bearing representative of the Carboniferous Limestone. To the cast of the llhinc valley, as already mentioned, the true C‘arboiiifei'oi1s Limestone loses its 110]-1n'L‘.1 character and assumes that of the Cuhn—a series of sli-ales, sandstones, greywackcs, and conglomerates, in which the abundant fauna of the limestone is reducc.d to a few mollusks (I’ro'dm'[u.~: alzﬁqzuts, I’. Iat1'ssz'i)tzLs, I’. scui2'rcli'euI¢ztz1s, I’o;s-£110-nuiit_i/it Berle:/'2',
 * 'o7u'ati'tcs.yiIucrz'cits, 07'thoccr(rs slriutuliun, &c.). The1'osi'donm/23/u

particularly characterizes certain dark sliales known as Posidonia schists. About 50 species of plants have been obtained from the Culm, typical species being C'(iIamz'lcs lra.u.s-ilionis, ;S'u_«/eiivrrm l 3 tIici'mi'mm, S[i'g2i2m'i'(L _/froitlcs, ;S'pIzciio12tc)'i's di.slcm.~', I '1/4-law.‘--4'.» tcnm_'/'oli'¢t. This flora bears a strong resemblance to that of the Calcifcrous Sandstones of Scotland. It is divided into the following groups Nonrii Aiiiziiic.-i.——Pocks corresponding in geological position and the general aspect of their organic content..- with the Carboniferous system of Europe are said to cover an area of more than 200,000 square miles in the l'nitcd States and British North America. The following table shows the subdivisions which have been estal.-lislied anion them :- C‘oal—measurcs,——a series of sandstones, shales, ironstoiies, coals, &c., varying from 100 feet in the interior eontineiital area tn 40t)0 feet in Pennsylvania, and more than 8000 feet in Nova Scotia.. The plant remains include forms of Lr_)u'r/o- dcndron, Sz'_i/z'lIm'ia, Stignmﬁrz-, CaIani..i'les, ferns, and coni- ferous leaves and fruits. The animal ft-rins cinbraec in th marine bands species of Spz')'1_'fn', I’/'0i7it«_'/its, Ifcllrrojzlum. Nrutlilus, &c. Among the sliales and carbonaccoiis bed»- numerous traces of insect life have been obtained, com- prising species related to the inay-fly and cockroach. « Spiders, scorpions, centipetlcs, liiiiiiloid crabs, and land snails like the modern I’u]2(L have also been met with. The fish remains comprise teeth and ichtliyodorulites of placoid genera, and a number of ganoids (1-.'iu'_i/7r1u's, (‘alum/il/:1I.~'. _l[cgalicIit7I_i/s, .’/u'.:o(lits, t'>:c.). Several labyrintliodonts occur, and true reptiles ai'e represented by one saurian gt-nu~ found in Nova Seotia, the I;'nsai(7°i(s. Millstone Grit,—a group of arcnaceoiis and sometimes con- glomerntie strata, with occasional c0al—scanis, only ‘.25 feet thick in some parts of New York, but swelling out to 1500 L feet in Pciiiisylvaiiia. Chester group.—Limestoncs, slialcs, and sandstones, some- times 600 feet. St Louis group.—l.iinestones with shale, in places '25-0 feet. Keokuk group.—Liiiiestone with chert layers ainl nodules. Burlington group.—Limestone, in places with cllt~l'l'. and horn- stone '25 to 200 feet. Kinderliook group.—Sandstones, slialcs, and thin limr-stones, 100 to 200 feet, resting on the Devonian black shale. The sub-Carboniferous groups are mainly marine liincstoiic-.<. but contain here and there remains of the cliai'a«-teristi«- (‘ar- boiiiferous land vegetation. Crinoids of many forins abound in the liinestones. A remarkable polyzooii, Art‘/ti/uctlcs, ocems in some of thfe bands. The bracliiopods :;rc pliiclly li'epi'csiciit]r,-cl b_V siecics 0 Sn'ri' er and I’roduc/us; tie ﬂint‘ iiranc is "Y 1l[_i/aliim, SL']I.li:."0{ll(8i,f_'l’Z'l'Cl(lupCC[I’7I, J'i(ci(Iu, Pin-7m, atid others; the ccphalopods by Orlhoccrrw, i'ruIti'lI1s, (:'om'riI1'/rs, C'_I/2'0CCI'.’!-5’. &c. The l".ui-opean genus of trilobite, I'hi'lIi'p.s-z'a, occurs Niiniei'oiis teeth and ﬁn-spines of selaehian fishes give a further point of resemblance to the l‘illl'0pCall Carboniferous l.lll1('Sl0ll(‘- Home of the rippled rain-pitted beds contain ampliil-ian foot- prints—the earliest American forius yet known. Carboniferous. Sub-Carboniferous.