gg THE GEOLOGIST. 



much. If the strata were spread out and piled up universally one over 

 the other this would be the height of our knowledge ; but they are not 

 so stacked nor are they concentrically enveloping. They are tilted up at 

 variousangles, and cutoff at their outcrops at the surface ; great bent domes 

 of rocks, once continuous over miles of country, have been carried wholly 

 away, and their materials re-deposited in the abysses of the sea. More- 

 over, these beds never were strictly horizontal except in a few cases ; 

 they are generally the produce of the littoral and marginal areas 

 of the pre-adamic oceans, and are most commonly wedge-shaped, thinning 

 out ,or thickening, one beneath the other. Geologists do not dwell 

 sufficiently upon this sea-marginal and inclined deposition of the rocks ; 

 they are too careless and too ready in their use of the term ''horizontal 

 stratification." There is very rarely any such thing in nature, 

 and this little fact makes a great difference. Suppose ten strata, 

 all inclined at the same angle, and each half-a-mile thick at its 

 outcrop. 



LiGN. 11.— Strata of equal thickness deposited at the same angle, and 

 sui>posed to be continuous in their diij. 



By the argument of original horizontality it is evident we should — by 

 walking over the country, and measuring the thickness or width of 

 the bods at their bassetting edges, a\ a-, d\ to allowing only for the 

 angle of inclination in our measurements — acquire a knowledge of the 

 nature and characters of these rocks equal to five miles in vertical depth 

 at the point r/". 



But these rocks were deposited with a diminishing or increasing 



