

COAST-LINES OF THE OLDER ROCKS. 119 



edges so as to undermine the rocks and convert them into precipices 

 on the seashore which are called cliffs. But when the deposits 

 shelve down gently into the water, there are no weak places in the 

 single stratum exposed which make it easy for the sea to cut a way 

 through the formation. Since the whole country, even in recent geo- 

 logical times, has been elevated from out of the ocean, terraces must 

 inevitably have been produced inland in this way at successive heights, 

 though in many cases the rounding influence of the action of rain has 

 more or less modified and obliterated the earlier work of the sea. But, 

 although dip and mineral structure may help to demonstrate the reason 

 why some coasts are worn away so as to be bordered by steep sea-cliffs, 

 such considerations give no insight into the origin of the outline of 

 the country or the way in which a sea-coast became a part of its 

 geological history. 



North and West Britain. In dealing with the British Islands, it 

 is necessary to have before us a map of this country and the adjacent 

 parts of Europe coloured geologically. It will then be seen that the 

 prevalent direction of the land forming the northern part of Britain is 

 not a matter of accident. The Hebrides, Shetland, and Orkney all run 

 in a direction from south-west to north-east. The strata in the part 

 of Scotland north of the Caledonian Canal have a similar direction. 

 The larger mass between the Moray Firth and the Firth of Forth is 

 also extended so as to be parallel to the Outer Hebrides, and this mass 

 has the Grampians for its axis. The southern part of Scotland is 

 similarly traversed by the Carrick, Moorfoot, and the Lammermoor 

 Hills, the rocks forming which extend through the country south- 

 west into Ireland. If now the direction of these strata be com- 

 pared with the rocks forming the Dovrefeldt, which is the mountain 

 axis of Norway, the Grampians will be seen to be but a southern 

 prolongation of that range, and, followed on into the north-west of 

 Ireland, the Mourne Mountains carry the chain still farther to the 

 south-west. No one who compares the west coast of Scotland and 

 the coast of Wales with the opposite coast of Ireland, can fail to see 

 that the strata of the two islands were originally continuous, and that 

 the Irish Sea and channels to the north and south have been hollowed 

 out by some cause which has not interfered with the direction in 

 which the strata extend. From a geological point of view, then, 

 Great Britain and Ireland may be treated as though they were one 

 land. Nor must it be forgotten that the moderate elevation of six 

 hundred feet would unite them together as a tableland, and prolong 

 the coast of Scotland in a north-east direction to within a few miles 

 of the Norwegian coast. Any geological student looking at a map 

 will see that this direction of the old Primary rocks forming these 

 countries is a consequence of the way in which the rocks at an early 

 period of geological history were thrown into folds so as to be elevated 

 from out of the sea. Each of the long strips of land forming Scot- 

 land and the isles west and north occurs as a saddle-like fold of the rocks 

 of the kind termed anticlinal. The narrow strips between the Firth 

 of Forth and the Firth of Clyde, and between the Moray Firth and 



