and Orography of the Earth's Surface. 299 



in the determination of ancient deltas, the course of ancient 

 rivers, and the depth of seas, as ascertained by lithophagi. 

 Still geodesy, and a knowledge of the bottom of seas, are 

 two things which would forward our views of these mighty 

 changes. It would enable us to trace over the whole of 

 the earth's surface, not only the abrading and upfilling 

 action of water, but also the extent of subsidences, and of 

 volcanic effects. At present we have only very small indi- 

 cations of these ; for instance, one seems warranted to ad- 

 mit to the west of Europe an old large continent or island, — 

 not only till the middle Tertiary period, but probably to 

 the old Alluvial time. The proofs of it are the state of de- 

 struction and steepness of the western shores, their islands, 

 the submarine forests, the direction of sea currents, the ele- 

 vation of neighbouring continents, the geographical distri- 

 bution of certain plants and animals in the now isolated west- 

 ern parts of Europe. 



To the east of North and South America old land seems 

 also to have subsided in the sea, and some summits of the 

 hills form now only islands. In the Pacific, Darwin shews us 

 an extensive subsidence in quite an opposite direction, viz., 

 from east to west, where now so many coral islands exist, or 

 are in formation. Along Western America, on the contrary, 

 is a deep sea, the bottom of which has a tendency to elevation. 

 The greatness of this action is proved by the high chains along 

 the sea- shores which run like the meridian. It is apparently 

 the mightiest on the earth's surface, and it is probable that it 

 gave rise also to the greatest subsidences in the Pacific. If we 

 pass to Asia, we find between Hindostan and Australia, with 

 its satellites, New Guinea, New Brittany, the Solomon's Isles, 

 New Caledonia, the New Hebrides, and New Zealand, the 

 best indications of considerable subsidences, namely, many 

 islands or divided continents, steep shores, rugged cliffs, and 

 volcanoes, as well as a very particular distribution of vege- 

 table and animal life. During the same time, probably, 

 subsidences took place around the Hindostan triangular 

 peninsula, and especially to the south of it. The same 

 may be said for the neighbourhood of South Africa and 

 on both sides of it ; for we find to the east fragments of 



