In some parts of the calcaire grossier round Paris, certain beds occur of a stone used in building, and called by the French geologists “Miliolite limestone.” It is almost entirely made up of millions of microscopic shells, of the size of minute grains of sand, which all belong to the class Foraminifera. Examples of some of these are given in Figs. 219 to 221. As this miliolitic stone never occurs in the Faluns, or Upper Miocene strata of Brittany and Touraine, it often furnishes the geologist with a useful criterion for distinguishing the detached Eocene and Upper Miocene formations scattered over those and other adjoining provinces. The discovery of the remains of Palæotherium and other mammalia in some of the upper beds of the calcaire grossier shows that these land animals began to exist before the deposition of the overlying gypseous series had commenced.

Lower Calcaire grossier, or Glauconie grossiere, B.1, [Table]—The lower part of the calcaire grossier, which often contains much green earth, is characterised at Auvers, near Pontoise, to the north of Paris, and still more in the environs of Compiègne, by the abundance of nummulites, consisting chiefly of N. lævigata, N. scabra, and N. Lamarcki, which constitute a large proportion of some of the stony strata, though these same foraminifera are wanting in beds of similar age in the immediate environs of Paris.

Soissonnais sands, or Lits coquilliers, B.2, [Table]—Below the preceding formation, shelly sands are seen, of considerable thickness, especially at Cuisse-Lamotte, near Compiègne, and other localities in the Soissonnais, about fifty miles N.E. of Paris, from which about 300 species of shells have been obtained, many of them common to the calcaire grossier and the Bracklesham beds of England, and many peculiar. The Nummulites planulata is very abundant, and the most characteristic shell is the Nerita conoidea, Lam., a fossil which has a very wide geographical range; for, as M. d’Archiac remarks, it accompanies the nummulitic formation from Europe to India, having been found in Cutch, near the mouths of the Indus, associated with Nummulites scabra. No less than 33 shells of this group are said to be identical with shells of the London clay proper, yet, after visiting Cuisse-Lamotte and other localities of the “Sables inférieurs” of Archiac, I agree with Mr. Prestwich, that the latter are probably newer than the London clay, and perhaps older than the Bracklesham beds of England. The London clay seems to be unrepresented in the Paris basin, unless partially so, by these sands.[[9]]

LOWER EOCENE FORMATIONS OF FRANCE.

Argile Plastique, C.2, [ Table]—At the base of the tertiary system in France are extensive deposits of sands, with occasional beds of clay used for pottery, and called “argile plastique.” Fossil oysters (Ostrea bellovacina) abound in some places, and in others there is a mixture of fluviatile shells, such as Cyrena cuneiformis ([Fig. 216]), Melania inquinata ([Fig. 216]), and others, frequently met with in beds occupying the same position in the London Basin. Layers of lignite also accompany the inferior clays and sands.

Immediately upon the chalk at the bottom of all the tertiary strata in France there generally is a conglomerate or breccia of rolled and angular chalk-flints, cemented by siliceous sand. These beds appear to be of littoral origin, and imply the previous emergence of the chalk, and its waste by denudation. In the year 1855, the tibia and femur of a large bird equalling at least the ostrich in size were found at Meudon, near Paris, at the base of the Plastic clay. This bird, to which the name of Gastornis Parisiensis has been assigned, appears, from the Memoirs of MM. Hébert, Lartet, and Owen, to belong to an extinct genus. Professor Owen refers it to the class of wading land birds rather than to an aquatic species.[[10]]

That a formation so much explored for economical purposes as the Argile plastique around Paris, and the clays and sands of corresponding age near London, should never have afforded any vestige of a feathered biped previously to the year 1855, shows what diligent search and what skill in osteological interpretation are required before the existence of birds of remote ages can be established.

Sables de Bracheux, C.3, [ Table]—The marine sands called the Sables de Bracheux (a place near Beauvais), are considered by M. Hébert to be older than the Lignites and Plastic clay, and to coincide in age with the Thanet Sands of England. At La Fère, in the Department of Aisne, in a deposit of this age, a fossil skull has been found of a quadruped called by Blainville Arctocyon primævus, and supposed by him to be related both to the bear and to the Kinkajou (Cercoleptes). This creature appears to be the oldest known tertiary mammifer.