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Here, therefore, if anywhere, we might expect to find hypogene formations of Eocene date breaking out in the central axis or most disturbed region of the loftiest chain in Europe. Accordingly, in the Swiss Alps, even the flysch, or upper portion of the nummulitic series, has been occasionally invaded by Plutonic rocks, and converted into crystalline schists of the hypogene class.
In the year 1852, a laborer named Bonnemaison, employed in repairing roads, observed that rabbits, when hotly pursued by the sportsman, ran into a hole which they had burrowed in a talus of small fragments of limestone and earthy matter lodged in a depression on the face of a steep escarpment of nummulitic limestone which forms the bank of a small brook near the town of Auvignac.
The period in time and the changes in physical geography represented by the nummulitic deposits are undoubtedly very great, while the remains of Middle Eocene and Older Eocene Mammals are comparatively few. The general facies of the Middle Eocene Fauna, however, is quite that of the Upper.
The Mediterranean still sends an arm up France, and with another arm encircles the Alpine mass; but the upheaval continues, and the great nummulitic sea is reduced to a series of extensive lakes, cut off both from the Atlantic and Pacific. The climate of Southern Europe is probably still as genial as that of the Canaries to-day. Palms still linger in the landscape in reduced numbers.
BRITISH. Bembridge fluvio-marine strata. Helen's series. FOREIGN. Gypsum of Montmartre, fresh-water with Palaeotherium. BRITISH. Bracklesham beds and Bagshot sands. FOREIGN. Calcaire grossier, miliolitic limestone. Nummulitic formation of Europe, Asia, etc. BRITISH. London Clay proper. FOREIGN. Argile de Londres, near Dunkirk. BRITISH. Upper white chalk, with flints.
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.
This is now generally believed to have been the case with the Silurian, Devonian, Carboniferous, Oolitic, and Cretaceous limestones and those nummulitic rocks of tertiary date which bear the closest affinity to the Eozoon reefs of the Lower Laurentian. It has a strike from north-west to south-east, nearly at right angles to the metamorphic strata of the Grampians.
In the new southern ocean another branch of these Thalamophores, the Nummulites, spreads with such portentous abundance that its shells sometimes alone, generally with other material make beds of solid limestone several thousand feet in thickness. The pyramids are built of this nummulitic limestone. The one-celled animal in its shell is, however, no longer a microscopic grain.
Some time during the Miocene epoch, possibly when the Himalayan chain was elevated, the bottom of the nummulitic sea was upheaved and converted into dry land, in the direction of a line extending from Abyssinia to the mouth of the Ganges. By this means, the Dekhan on the one hand, and South Africa on the other, became connected with the Miocene dry land and with one another.
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." Manual, p. 232. A still more marked case follows on the next page.
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