When we have once arrived at the conviction that the nummulitic formation occupies a middle and upper place in the Eocene series, we are struck with the comparatively modern date to which some of the greatest revolutions in the physical geography of Europe, Asia, and Northern Africa must be referred. All the mountain-chains, such as the Alps, Pyrenees, Carpathians, and Himalayas, into the composition of whose central and loftiest parts the nummulitic strata enter bodily, could have had no existence till after the Middle Eocene period. During that period the sea prevailed where these chains now rise, for nummulites and their accompanying testacea were unquestionably inhabitants of salt water. Before these events, comprising the conversion of a wide area from a sea to a continent, England had been peopled, as I before pointed out (p. 267), by various quadrupeds, by herbivorous pachyderms, by insectivorous bats, and by opossums. Almost all the volcanoes which preserve any remains of their original form, or from the craters of which lava streams can be traced, are more modern than the Eocene fauna now under consideration; and besides these superficial monuments of the action of heat, Plutonic influences have worked vast changes in the texture of rocks within the same period. Some members of the nummulitic and overlying tertiary strata called _flysch_ have actually been converted in the central Alps into crystalline rocks, and transformed into marble, quartz-rock, micha-schist, and gneiss.[11] Eocene Strata in the United States.—In North America the Eocene formations occupy a large area bordering the Atlantic, which increases in breadth and importance as it is traced southward from Delaware and Maryland to Georgia and Alabama. They also occur in Louisiana and other States both east and west of the valley of the Mississippi. At Claiborne, in Alabama, no less than 400 species of marine shells, with many echinoderms and teeth of fish, characterise one member of this system. Among the shells, the _Cardita planicosta,_ before mentioned (Fig. 191), is in abundance; and this fossil and some others identical with European species, or very nearly allied to them, make it highly probable that the Claiborne beds agree in age with the central or Bracklesham group of England, and with the calcaire grossiere of Paris.[12] Higher in the series is a remarkable calcareous rock, formerly called “the nummulite limestone,” from the great number of discoid bodies resembling nummulites which it contains, fossils now referred by A. d’Orbigny to the genus _Orbitoides,_ which has been demonstrated by Dr. Carpenter to belong to the foraminifera.[13] That naturalist, moreover, is of opinion that the Orbitoides alluded to (_O. Mantelli_) is of the same species as one found in Cutch, in the Middle Eocene or nummulitic formation of India.