GEOGNOSY AND GEOLOGY. 185 
yellowish, or reddish in color, and bituminous. Adhesive slate is sometimes 
imbedded in the calcareous marl, as also freestone and some other silicious 
substances. A compact celestine sometimes occurs. Clay, as potter’s clay, 
marl clay and loam, of which some are important in the arts, as the Argile 
plastique and the London clay. 
Sand and sandstones, the former predominating, and sometimes marly, 
sometimes argillaceous or ferruginous. The sandstones exist sometimes as 
argillaceous, sometimes as marly or ferruginous sandstone; in the Jatter case 
they often have a tubular, rough appearance. 
Among the subordinated masses belong gypsum beds ; among them the 
Paris bone gypsum. This is sometimes compact, sometimes sparry, and 
closely mixed with carbonate of lime. In the tertiary deposits gypsum again 
occurs in mar!; also peat and iron-stone. 
This calcaire grossier or coarse limestone is highly developed in the 
Paris basin, and has there been carefully studied, especially by Cuvier and 
Brogniart. The strata occur in the following order : 
Beneath les the pisolitic limestone (calcaire pisolitique), a marine 
formation, characterized by Corals, Echini, Dentalium, Serpula, Cytherea, 
Venus, Cardium, Arca, Solen, Natica, Cerithium, Fusus, &c. Cerithium 
is found in great abundance. 
Next comes a plastic clay (Argile plastique), whose purer lower bed is 
separated from the impure upper by a layer of sand. It contains both 
fresh water and marine shells, as Planorbis, Paludina, Melanopsis, Cyclas, 
and Ostrea. Also remains of Crocodiles and Chelonia, as the genus Hmys. 
Then follows a purely marine formation, the calcaire grossier proper, 
whose lower beds are of an arenaceous texture. Upon the limestone mass 
lies a sandstone of tolerable firmness, much used in Paris for building 
purposes ; on this, again, rest beds of marl and firmer limestone. The lower 
strata of the calcaire grossier contain nummulites; the middle exhibits a 
vast number of fossils, the most abundant of which are: of plants—Hquisetum 
brachyodon, Pinus defrancti, Confervites, Endogenites echinatus, Flabellaria 
parisiensis, Caulites, Potamophyllum multinervis: of vertebrata—Paleo- 
therium, Lophiodon, and Chelonia: of shells—Miulliolites, Cardium obliquum, 
Lucina saxorum, Ampullaria, Cerithium, Orbitolites plana, Cardita 
avicularia, Oculites elongata, Alveolites milium, Turritella imbricata, 
Calyptrea trochiformis, Pectunculus pulvinatus, Cytherea nitidula and 
elegans, Turritella multisulcata, Ostrea flabellula, Natica epiglottina, 
Trochus agglutinans, Cerithium cornucopia, &c. 
Upon the calcaire grossier rests a silicious lime (calcaire silicieux de St. 
Ouen), in the lower part of which fluviatile and marine shells are found 
intermixed, while in the upper, fluviatile alone are met with. 
Then follows the marl with the bone gypsum, also fresh water formations, 
as they are filled with Cyclas, Paludina, Planorbis, &c. The bed attains a 
thickness of 170 feet, and, in addition to the fossils already mentioned, 
contains likewise fishes and mammalia; of the latter, Paleotherium, 
Anoplotherium, Adapis, Didelpnys, &c. There are also remains of birds, 
crocodiles, sea and fresh water turtles, &c. 
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