of Refuge on the East Coast of Scotland. 307 



character of these defects, it is necessary to advert, however 

 briefly, to a few elementary truths of physical geography, 

 which may not perhaps be generally attended to, although 

 highly ilkistrative of the subject. 



When we examine a Valley of any extent with the eye of 

 a geologist, we shall generally find that the rocks which ex- 

 ist in the trough, are softer and. more easily acted upon than 

 those which form the bounding ridges. Interspersed portions 

 of harder rock may be occasionally found among the softer 

 materials, but those will merely cause inequalities in the 

 valley, and mark, by their elevation, the resistance which has 

 been offered to the disintegrating forces which have reduced 

 the contiguous portions to a lower level. 



When we examine a Bay, or indentation on the coast, we 

 generally find analogous appearances. The softer beds have 

 been acted upon, broken up, and removed by the action of the 

 ripple or wind-waves ; while the harder materials remain and 

 constitute those promontories or nesses, which form the lateral 

 limits of the recess or creek. Even in the bay, as in the 

 valley, certain portions of harder rock may have existed, and 

 such will usually be preserved as islets or skerries, to mark 

 the abrasion which has taken place around. 



If, then, the softness of the strata be the primary condition 

 which gives rise to valleys and bays, we may expect to find 

 in general a valley, on reaching the sea-shore, terminating in 

 a bay, while a bay will be a tolerably sure indication of a 

 landward valley. Several rather interesting examples, in il- 

 lustration of these statements, may be observed in this imme- 

 diate neighbourhood. 



The bay of Aberdeen, with its lateral nesses of gneiss, 

 seems to have been excavated in a deposit of old red sand- 

 stone, several patches of which occur in the neighbourhood, 

 and attest its former more extended distribution. The 

 bay of Nigg, with similar lateral nesses, appears to have been 

 produced by the yielding of soft strata of mica-slate. The 

 bay of Stonehaven has been excavated in comparatively soft 

 strata of grey sandstone, with its northern ness of compact 

 mica-slate, and its southei'n ness of old red sandstone con- 

 glomerate. To the south of Stonehaven, and in the neigh- 



