128 W. H. HOBBS REPEATING PATTERNS IN STRUCTURE OF LAND 



study of the dominant lines in the landscape, and at many places also of 

 the structural elements of the nearer rock-masses. On this bleak, rocky 

 coast there is little protection from vegetation, and the steep gradients of 

 the surface keep the rock largely bare of mantle debris. Frost action is 

 apparently the dominant weathering process — a process which always 

 emphasizes the importance of planes of separation within the rock, since 

 thus only can the prying stresses of freezing water be made effective. The 

 conditions here are, therefore, ideal for a study of the influence of rock 

 structure upon the relief forms. 



DIFFERENT ORDERS OF SPACE UNITS 



One whose attention was directed to the subject could hardly fail to 

 notice that throughout the cruise the near profiles whenever visible indi- 



FiGURE 4. — Illustrations from the Norwegian Coast 



a, Characteristic near profile on ttie Norwegian coast. There is a broader subdivision 

 into nearly equal units, which are again subdivided into others of a lower order of mag- 

 nitude. 6, Diagram to illustrate the manner of subdivision of island profiles on Norwe- 

 gian coast. Specially wide joints recurring at regular intervals permit of excessive 

 frost work. 



cated a quite remarkable subdivision into nearly equal spaces, which in 

 turn were subdivided in a similar manner into smaller space units. The 

 manner of this subdivision is schematically expressed in figure 4a and by 

 photographs in plate 7. 



The isolated islands not infrequently represent each a block unit of one 

 or the other of the orders of magnitude described (plate 7, figure 2). 

 Whenever the steamer approached the islands of the larger order partic- 

 ularly, it was possible to observe well developed vertical joints intersecting 

 the cliff faces, with the crest of the island depressed at regular intervals 

 in more or less sharply defined valleys which were each located above 

 more midely gaping joints (see figure 4& and plate 7). 



Joint intervals of a higher order of magnitude than those generally 

 recognized are to be made out with especial clearness in figure 5, because 



