﻿346 lord avebury on an [May 1905, 



Figs. 5-8 (pp. 350-51) represent a series taken in January. The 

 machine was packed as follows : — 



4 inches of sand. 



Thin oilcloth. 

 If inches of sand. 



Cloth (medium thickness). 

 If inches of sand. 



Thin oilcloth. 

 If inches of sand. 



Cloth, as before. 



2 inches of sand. 



The screws were then turned 3 inches. 



Fig. 5 (p. 350) represents the upper layer of cloth, thrown into 

 sharp ridges. Fig. 6 (p. 350) represents the layer of oilcloth. The 

 general plan is the same, but the ridges are fewer. Fig. 7 (p. 351) 

 represents the second, lower, layer of cloth. The ridges are 

 numerous, and have a well-marked tendency to arrange themselves 

 in squares, as, for instance, in Kjerulf's map, 1 but are less pronounced 

 than they would have been if they had not had the oilcloth over 

 them. Fig. 8 (p. 351) represents the lower layer of oilcloth : the 

 ridges are less numerous than in the softer and more flexible cloth. 



For contrast, I give figs. 9-13 (pp. 352-54), which represent 

 another series taken at the beginning of this year. The machine 

 was packed as follows : — 



3 inches of sand. 



Cloth as before. 

 I.] in .lies of sand. 



Linoleum. 

 If inches of sand. 



Cloth. 

 If inches of sand. 



Linoleum. 

 2 inches of sand. 



The screws were then turned 3 inches, reducing the square from 

 24 inches to 22. 



Fig. 9 (p. 352) represents the upper layer of cloth, which was 

 similar to that used in the preceding series. It will be seen, how- 

 ever, that the folding is altogether different, owing to the influence 

 of the underlying linoleum. This is shown in fig. 10 (p. 352). The 

 bold sweeps are striking, and the curved valley will recall many 

 which occur in Nature. Fig. 11 (p. 353) represents the lower cloth, 

 which, as will be seen, shows more numerous minor folds. Fig. 12 

 (p. 353) represents the lower layer of linoleum. The general 

 arrangement is the same, but the folds are sharper ; in fact, the 

 linoleum was broken along the principal ridges. Fig. 13 (p. 354) 

 gives a lateral view. 



On the other hand, the case is very different if we introduce a 

 stiff layer of some substance such as cement. This cannot throw 

 itself into folds, but breaks and tilts itself up, assuming the 



1 ' Geologie des siidlichen & mittleren Norwegen ' 1880, p. 330, figs. 279 

 & 280. 



