38 FKIDIJOF NAN.SKN. M.-X. Kl. 



TIic arj^ilaccous sliists aii<l sliaics arc easily dcniulcl iii lliis manner. 

 'J'lie nodules of lime-stone may he more resistant, and tliey llierefore often 

 project somcwliat above the surface oi the surrounding shales. 



As J/'i^. 17 shows, the rock of the higher parts of the ledj^es has the 

 very rough surface typical for rocks disintegrated by frr^st. In some 

 places where the rock surface is extremely rcjugh the relief of the many 

 projecting ridges and blocks may amount to nearly one metre. The edges 

 of the projecting rocks, on the outer part of the ledges as well as further 

 in, are but slightly rounded by the wave action, which has obviously been 

 of very little direct importance for the original forination of these ledges. 

 The surf at high water lias, however, been of great indirect importance 

 by washing away the débris formed by the frost erosion. 



Where the ledges are low, and slope gently seawards below average 

 sea-level, as in some part of the shore represented in Fig. 18, the solid rock- 

 surface is more or less covered by a layer of stones of different sizes. It 

 is possible that the wave erosion may here have denuded somewhat the 

 outer part of the ledges. The stones are rolled up and down the beach 

 by storms from the south and south-east, which always cause high-water 

 and may have great effect by a vigorous surf. The rock-surface of the 

 lower levels show indications of wave erosion, though it has also to some 

 extent been disintegrated by frost. 



The stones have obviously been broken loose from the solid rock by 

 frost disintegration. There are all stages from a great number of angular 

 stones recently disintegrated, and consisting to a great extent of diabase, 

 to rounded, wave-worn pebbles, which greatly consist of the more resistant 

 parts of the argilaceous shist, especially the calcareous nodules. 



These ledges have been developed in recent time after the land had 

 been elevated very nearly to its present shore-level ; and there has obviously 

 been no appreciable elevation of the land after their formation. The sur- 

 face of the ledges shows no traces of glacial erosion, but the surface of 

 dykes of diabase in several places projecting in the shore-line at the outer 

 edge of the ledge is rounded and striated by glacial erosion, and so is the 

 upper surface of the dyke of diabase to the right in Fig. 17, forming the 

 cliff backing the ledge. The low skerry seen in the background, behind the 

 bath-house to the right, is also rounded and striated by glacial erosion. 



In many other places along this shore one also finds rock-surfaces, 

 chiefly of dykes of diabase, which are rounded and striated by glacial 

 erosion. They are sometimes situated near sea-level outside the shore- 

 ledge, and sometimes above it. 



This shows that the rocks of the shore had been scoured and rounded 

 by the glaciers of the last glacial period, before they were attacked by the 

 shore-erosion, after the shore had been elevated to its present level. The 

 argilaceous shists were then easily disintegrated by frost, and were cut 

 back bv the shore-erosion, while the dvkes of dial)ase were much more 



