Page:Encyclopædia Britannica, Ninth Edition, v. 10.djvu/373

Rh casrAcEoUs.] much wider an extension than the English type of the Cretaceous system that it should be regarded as really the normal develop- ment. It ranges through the Alps into Dalmatia, and round the great Mediterranean basin far into Asia. Giimhel has proposed to group the European Cretaceous rocks into three great regions :— (l) the northern province, or area of white chalk with Bclcmmlclla, Table showing the Subclivisions 0;’ the Cretaceous System. in the IVest of Europe. Northern France. l'orth-West Germany aud Denmark. Southern l-England. 1.-mnce_ Faxoe chalk. Craie Maestrit-lit chalk (p. 360). Danicn, supérieure et ealcaire piso- litiquc(p.360). with Craie blanche Oberquadersandstcin (Belemnitella (lﬁelenmitella mu- mucronala). cronala, Ace.) Craie (Belem- m'IeIIa quad- ratas). Lower Chalk without Craie (.l{icras- Oberquadersandstein ﬁints. tel‘ cor-an- (Jlirraster cor-an- guinum). guinum). mar- .litt¢-lquadcr. .Iittel- Calcaires it pliincr (Inoeeramus Ilippmites ('1u:i'eri and I. labI'- cornu-ra¢'cz'- atus). mun. et 2:. Ra- diolilea cornu- pastoris. Calcaires mar- ncux ( Increm- mua (abiatus). Upper Chalk tlints. Calcaircs it rudistes (Ra- diam es). So.-nonian. E (‘Fill-—l_li Marl. Craie l'.lCl1S0. Turoniau. Craie nieuse Chloritic Marl. giauco- Upper (irccnsand. Gres vert supé- Untcrquaacr, Unfc1'- cal;-nil-cs 33, rieur pliiner (Ammoniles Caprotina!ri- Rotomagensis, A. angularzs, ct t'arian.s). it Ammo-m'le.< Rolomagensis (.'euoinauian.i Amie“. argilc Flnmmenmergcl (.»tri- Albien, sables mnmcusc olll cula gryphteoides). ct gres vcrts sableuse. Clay(BeIemnitc.smini- ou ferrugi- mus). neux 21 Turn‘- lites. APHCH. argilcs Marls, &c. A mmon- Aptien (Orbi- h plieatulcs. iles tarde_fur¢'atu.¢, tulina lenlicu- Belemniles Eiraldi) Iaris). Clays (Belenmites Calcaire ii‘ Brtuisvicensis). caprotincs. Ancyloceras beds. Gault. Gault. Urgonien. Lower Grecnsand. Argiles ostré- llils clay (Hilsthon) Neocomicn ennes (E.ro- with Ammonites supérieur gg/ra subpli .'ort'cus, Arc. (Toroceras €010. 0817'“ complanalus), Leynier-ii). cnlcnirc Spalangus. lPunﬁeld ‘and Tealby pieds and Calcaires néo-_Ilils con-Weald comiens et glomerate clay (J12- marncs blcucs'(To1'oceras lania, Cy. (T01-astercom-'compIana- rum). planatus). lus, Rhyn- chonella depressa). T:-—-— with Lower-part Sable blanc ct seams. of Speeton fcrrugineux. _Clay. Neocomien moyen, cal- caire it Apty-I thus. I Wcald middle Clay and .part of Hastings l.'p(-eton 'Sand. Clay. l I l comprising England, northern France, Belgium, Demnark, Vest- phalia; (2) the llercynian province, or area of Exogym col-zunba, embracing Bohemia, Moravia, Saxony, Silesia, and central Bavaria ; and (3) the southern province, or area of hippurites, including the regions south of the crystalline axis of France, the Alps, and southern Europe. The 'ealden beds, with the Hastings Sands and Veald Clay, are found in north-west Germany. They contain abundant remains of terrestrial vegetation, which is sometimes aggregated into thin seams of black glancing coal, occasionally even as much as 6; feet thick. The marine or typical Neocomian series attains a great development among the eastern Alps, where it consists mainly of massive white and grey limestoncs, divided into zones according to their characteristic fossils. Some geologists place in it a part of the massive Vienna sandstone (Viener Sandstein) which enters so largely into the structure of the outer Alps. The massive arena- eeous formation formerly massed together under the general name of Quader-sandstein, but now found to be the equivalent of the calcareous bands of other regions, and capable of subdivision into the chief normal groups, forms a conspicuous feature in Saxony and Bohemia, as in the great gorge of the Elbe and the picturesque crags and pinnacles of Saxon Switzerland. From the Upper Creta- ceous beds, in the neighbourhood of Aix-la—Chapelle, consisting of wlute sands and laminated clays 400 feet thick, a large number of terrestrial plants have been obtained. The number of species is estimated at more than 400. Of these 70 or 80 are cryptogams, chieﬂy ferns (Gleiclten-z'a, Lygodium, Asplenizmz-, &c.) ; there are l'eueemiau or lllls. Néoconiien in-1 férieur (Toro- eeras Cam pechei). Dcister- sandstein coal GEOLOGY 359 numerous conifers (some akin to Sequoia), and three or four kinds of screv-pine (Pandanus). This ﬂora has a much more modern aspect than any other yet found in Secondary formations. But its most important feature is the occurrence of numerous true exogenous plants—the earliest yet found in Europe. The prevalent forms are Proteaccce, many of them being referred to genera still living in Australia or at the Cape of Good Hope. There occur also species of oak, bog-myrtle, «Sac. These interesting fragments serve to indi- cate the modern character of the ﬂora of Europe towards the close of the Cretaceous period, and to show that the climate, doubtless greatly warmer than that which now prevails, nourished a. vegeta- tion like that of some parts of Australia or the Cape. Further information has been afforded regarding the extension of this ﬂora by the discovery in North Greenland of a remarkable series of fossil plants. From certain Lower Cretaceous beds of that Arctic region, lleer has described 30 species of ferns, 9 cyeads, and 17 conifers; while, from the Upper Cretaceous rocks of Noursoak, he enumerates species of poplar, ﬁg, sassafras, credneria, and magnolia. NORTH AMEI’.ICA.——Tl1e recent surveys of the western territories of the United States have greatly increased our knowledge of the Cretaceous system on the American con- tinent, where it is now known to cover a vast expanse of surface, and to reach a thickness of sometimes 10,000 feet- Sparingly developed in the eastern States, from New Jersey into South Carolina, it spreads out over a wide area in the south, stretching round the end of the long Palaeozoic ridge from Georgia through Alabama and Tennessee to the Ohio ; and reappearing from under the Tertiary formations on the west side of the Mississippi over a large space in Texas and the south-west. Its maximum development is reached in the western States and Territories of the Rocky Mountain region—Wyoming, Utah, and Colorado. Cretaceous rocks have likewise been detected in Arctic America near the mouth of the Mackenzie River. Much controversy has been carried on among American geologists regarding the upper limit of the Cretaceous system, some maintaining, from the character of the plants and of the shells, that the great plant-bearing series termed the Lignitic is of Tertiary age, others insisting, from the occurrence of true Cretaceous shells in and above the Lignitic series, that it must belong to the Cretaceous system. In the Upper Missouri region Hayden and Meek established the following subdivisions :— 5. Fox Hills group. —Sandstones and sandy clays (Belem- nitclla, 1'autilu.3, A-mmonitcs, Baculitcs, Jllosasaurus, &c.) ............................................................. .. 00 ft. 4. Fort Pierre group.———Plastic clays (Ammonitcs, Scaphitcs, Inoccramus, &c.) .............................................. .. 700 ,, 3. Niobrara group.—Caleareous marl (Ostrca congesta, Inoccra-mus problcmaticus, ﬁsh remains),' ............. .. 200 ,, 2. Fort Benton group.—Clays and limestoncs (Scaphitcs, Ammonitcs, Pholadomya, &c.) ............................ .. 800 ,, 1. Dakotah group.—Sandslones, clays, and seams of lig- nite, with vast numbers of dicotyledonous leaves; a few marine shells. This is the great repository of the Cretaceous ﬂora ........ ............................ .. 400 ,, American Cretaceous fossils include the earliest dicotyledonous plants yet found on this continent, upwards of 100 species having een found, of which one-half were allied to living American forms. Among them are species of oak, willow, poplar, beech, maple, hickory, ﬁg, tulip—t1ee, sassafras, sequoia, American palm (Sabal), and cycads. The more characteristic mollusea are species of Tere- bratula, Ostrca, Gryplzwa, Inoccramus, Ilippuritcs, I.‘a(lz'olz'tes, Amlmonites, Scaphitcs, Ilamitcs, Baculites, Bclcmnitcs, A ncyloceras, and Turrilitcs. Of the ﬁshes of the Cretaceous seas 97 species are known, comprising large predaceous representatives of modern or osseous types like the salmon and saury, though cestracionts and ganoids still ﬂourished. But the most remarkable feature in the American Cretaceous fauna, as at present known, is the great number, variety, and size of the reptiles. According to the enume- ration of Cope, who includes, however, in his list the Lignitic group here placed among the Tertiary formations, there are known at present 18 species of deinosaurs, 4 pterosaurs, 14 crocodilians, 13 sauropterygians or sea-saurians, 48 testudinates (turtles, &c.), and 50 pythonomorphs or sea-serpents. One of the most extraordinary of these reptilian forms was the Elas-7nosaurus—a huge snake-like form 40 feet long, with slim arrow-shaped head on a swan-like neck rising 20 feet out of the water. This formidable sea-monster “ pro- bably often swam many feet below the surface, raising the head to the distant air for a breath, then withdrawing it and e.'ploring the