HOW WERE THE EOCENES OF ENGLAND DEPOSITED? 291 
Australian land across the equator, and forming bridges by which 
the most temperate plants might have migrated from Australia 
and from America without being killed by heat. Even with the 
supposed elevation of 2,000 fathoms the ridge would have been 
sufficiently elevated to permit the passage of all the plants 
yet found in Tertiary beds. Without pursuing the subject 
further, the fact remains that at all events a great tract of land 
existed where sea is now, and that Cornwall, the Scilly and Chan- 
nel Isles, Ireland, and Brittany, are the remains of its elevated 
land. It must, at least, have been as large as France, Swit- 
zerland, and Germany, although unconnected with southern 
Europe. There is, in addition, an ever-increasing mass of botani- 
cal and zoological evidence showing that the Atlantic Isles 
formerly must have been portions of a great continent ; and Wol- 
laston, from a study of the insects of the Azores, Madeira, &c., 
quite recently has been able emphatically to reiterate this fact. 
It is probable that throughout the whole of the Eocene 
period this land was slowly sinking, and opinion has gained 
ground that the former connection with Australia and Africa 
became severed during that time. The great submergence, 
however, did not take place until Miocene times, and was co- 
incident with the elevation of the Alps. The upheaval of the 
Alps was doubtless directly connected with the sinking of a 
correspondingly great area, and the magnitude of the subsidence 
may yet be ascertained by the mass of the elevation. While 
the London Clay was accumulating, the sea still rolled over some 
of the loftiest summits of the Alps, and the changes that have 
subsequently occurred equal in amount the conversion of sea 
into a continent as large and lofty as that of Europe, Asia, and 
the north of ‘Africa, and of land into sea to at least an equal 
extent. “ The grand sinking down of the conglomerate of the 
molasse more than a mile vertically did not begin till all the 
Eocene movements had terminated, and the upheaval of the 
same molasse took place at a later period, so that it reached at 
length its present altitude of 3,000 and 4,000 feet above the 
sea.” * In face of these stupendous movements, the oscillations, 
whose effects we have endeavoured to trace in England, appear 
insignificant, the total sum of the depression in Eocene times 
not exceeding 1,800 feet. Our Eocene area, however, was but 
the border land, the axis between elevation and subsidence, and, 
although continually shaken, participated decidedly in neither 
movement, each tendency being constantly checked. 
Vast as must have been the lapse of time during the accu- 
mulation of our some 2,000 feet of Eocene strata, still greater 
appears the interval, of which we have no record in Europe, 
between the Chalk and Eocene. The almost complete change 
* Lyell, “ Annual Address to tlie Geological Society,” 1850. 
