114 



THE GEOLOGIST. 



the lines. A, B, G, H, represent the direction of the lami- 

 nated bed, with reference to the sectional view of the exca- 

 vation C, D, E. It will be seen that these beds are 

 intersected at an angle by this excavation, leaving various 

 triangular masses of earth on the right hand side (E. G. H, 

 E. F. A,) the base lines of which are at an angle considerably- 

 elevated from the horizontal line. Now from an examination 

 of the causes which are conducive to the occurrence of slips, 

 which we have recorded, it will be found that these circum- 

 stances may be classified under the second and the third 

 divisions ; for the line of deposition A. F, being as stated, the 

 line of drainage, and the moisture percolating in that direction, 

 so soon as the position of the super-incumbent mass of earth 

 is rendered insecure by the removal of any portion of the 

 earth at its base (along this line) a slip necessarily takes place. 



We have given a perspective view of the deep cutting on 

 the Croydon line (Fig. 2) in order to demonstrate these 



Fig. 2. 



arguments yet more clearly. The line A. E is that of the 

 slope of the embankment, and the lines A. B, C. D the lines 

 of the dip : the first slip occurred in that portion, and was of 



