278 
ELEMENTS OF GEOLOGY. 
have arisen from confounding an allied genus, Orbitoides, 
with the true IMummulite. 
Fig. 223. 
NuDimuUtes Puschi, D’Archiac. Peyi-ehorade, I’yrenees. 
a. External surface of one of the uumninlites, of which longitudinal sections 
are seen in the limestone. 6. Transverse section of same. 
When we have once arrived at the conviction that the 
nummulitic formation occupies a middle and upper pla’ce in 
the Eocene series, we are struck with the comparatively 
modern date to which some of the greatest revolutions in the 
physical geography of Euroj^e, Asia, and ISTorthern 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 Mid¬ 
dle Eocene period. During that period the sea prevailed 
where these chains now rise, for nummulites and their ac¬ 
companying 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 peo¬ 
pled, 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 monu¬ 
ments 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 have actually been converted in the cen¬ 
tral Alps into crystalline rocks, and transformed into marble, 
quartz-rock, micha-schist, and gneiss.^ 
Eocene Strata in the United States. —In North America 
the Eocene formations occupy a large area bordering the At- 
* Murchison, Quart. Journ. of Geol, Soc., vol. v., and Lyell, vol. vi. 1850. 
Anniversary Address. 
