TRANSACTIONS OF SECTION E. 799 



tlie rock8. But no long inlets or fiords can result from such action. At most the 

 harder and less readily demolished rocks will form headlands, while shallow bays 

 will be scooped out of the more yielding masses. In short, between the narrower 

 and broader parts of the eroded shelf or terrace a certain proportion will tend to 

 be preserved. As the shelf is widened, sedimentation will become more and more 

 effective, and in places may come to protect the land from fuither marine erosion. 

 This action is especially conspicuous in tropical and subtropical regions, which are 

 characterised by well-marked rainy seasons. In such regions immense quantities 

 of sediment are washed down from the land to the sea, and tend to accumulate 

 along shore, forming low alluvial flats. All long-established coast-lines thus 

 acquire a characteristically sinuous form, and perhaps no better examples could bo 

 cited than those of Western Africa. 



To sum up, then, we may say that the chief agents concerned in the develop- 

 ment of coast-lines are crustal movements, sedimentation, and marine erosion. All 

 the main trends are the result of elevation and depression. Considerable 

 geographical changes, however, have been brought about by the silting up of those 

 shallow and sheltered seas which, in certain regions, overflow wide areas of the 

 continental plateau. Throughout all the ages, indeed, epigene agents have striven 

 to reduce the superficial inequalities of that plateau by levelling heights and 

 fining up depressions, and thus, as it were, flattening out the land surface and 

 causing it to extend. The erosive action of the sea, from our present point of 

 view, is of comparatively little importance. It merely adds a few finishing touches 

 to the work performed by the other agents of change. 



A glance at the geographical evolution of our own continent will render this 

 sufficiently evident. Viewed in detail, the structure of Europe is exceedingly 

 complicated, but there are certain leading features in its architecture which no 

 profound analysis is required to detect. We note, in the first place, that highly 

 disturbed rocks of Archaean and Palaeozoic age reach their greatest development 

 along the north-western and western borders of our continent, as in Scandinavia, 

 the British Islands, North-west France, and the Iberian Peninsula. Another belt 

 of similarly disturbed strata of like age traverses Central Europe from west to 

 east, and is seen in the south of Ireland, Cornwall, North-west France, the 

 Ardennes, the Thiiringerwald, the Erzgebirge, the Rieseugebirge, the Bohmerwald, 

 and other heights of Middle and Southern Germany. Strata of Mesozoic and 

 Cainozoic age rest upon the older systems in such a way as to show that the latter 

 had been much folded, fractured, and denuded before they came to be covered 

 with younger formations. North and north-east of the central belt of ancient 

 rocks just referred to, the sedimentary strata that extend to the shores of the 

 Baltic and over a vast region in Russia range in age from Palaeozoic down to 

 Cainozoic times, and are disposed for the most part in gentle undulations : they 

 are either approximately horizontal or slightly inclined. Unlike the disturbed 

 rocks of the maritime regions and of Central Europe, they have obviously been 

 subjected to comparatively little folding since the time of their deposition. To the 

 south of the primitive backbone of Central Europe succeeds a region composed 

 superficially of Mesozoic and Cainozoic strata for the most part, which, along with 

 underlying Palaeozoic and Archaean rocks, are often highly flexed and ridged up, 

 as in the chains of the Jura, the Alps, the Carpathians, &c. One may say, in 

 general terms, that throughout the whole Mediterranean area Archaean and 

 Palafcozoic rocks appear at the surface only when thej' form the nuclei of mountains 

 of elevation into the composition of which rocks of younger age largely enter. 



From this bald and meagre outline of the general geological structure of 

 Europe, we may gather that the leading orographical features of our continent 

 began to be developed at a very early period. Unquestionably the oldest land 

 areas are represented by the disturbed Archaean and Palaeozoic rocks of the 

 Atlantic sea-board and Central Europe. Examination of those tracts shows that 

 they have experienced excessive denudation. The Archaean and Palaeozoic masses, 

 distributed along the margin of the Atlantic, are the mere wrecks of what, in 

 earlier ages, must have been lofty regions, the mountain-chains of which may well 

 have rivalled or even exceeded in height the Alps of to-day. They, together with 



