CLAY AND ITS MODE OF OCCURRENCE. 19 



c, which is capped by bed 2. If one did not know that the beds 

 rose in that direction, it might be assumed that bed 1 passed into 

 bjed 2, because they are at the same level. This dipping of the 

 layers or beds sometimes accounts for the great dissimilarity of 

 rjeds at the same level in adjoining pits. 



Fig. 13. 



Inclined strata, showing rise of the bed above sea level, when followed up the slope 



or dip. 



Where a bed of clay is found outcropping at the same level on 

 two sides of a hill it is reasonable to assume that it probably ex- 

 tends from one side to the other, but it is not safe to predict it with 

 certainty, for as has been mentioned above, clay beds may thin out 



Fig. 14. 



Outcrops of a clay bed on two sides of a hill and its probable extension into the same. 



within a short distance. Furthermore, the overlying material or 

 overburden will become thicker towards the centre or summit of 

 the hill, so that even if present, the clay may be economically un- 

 workable. (Fig. 14.) 



