Ch. XIII.] THE INCLINED POSITIONS OF STRATA. 259 



in diameter, with a length of twelve inches ; and their posi- 

 tion is perpendicular to the plane of the stratum, which, 

 when this latter is at an angle of 40, causes the coralline 

 tubes to form an angle of 50." 



The author means, we presume, that the tubulites form an 

 angle of 50 with the horizon in the opposite direction to that 

 of the plane of the stratum. Another argument, to which 

 great importance has been attached, is the position of the 

 strata of conglomerates, which are sometimes inclined at con- 

 siderable angles. It is asked, if these strata be in their 

 original situation, how could the large rounded pebbles, of 

 which they frequently consist, have remained in their places 

 before the consolidation of the rock ? Would they not, fol- 

 lowing the laws of gravity, have rolled down, and formed a 

 talus, or heap, instead of regular strata ? It is, therefore, 

 contended, that they must have been formed in a horizontal 

 position : but we think that in this case much may be said on 

 the other side of the question. 



These rocks occur in such different situations relatively to 

 other strata, and under such varied circumstances, that it 

 would be a long enquiry to examine into each distinct case : 

 in some, we allow, the highly inclined layers could not have 

 been deposited successively in such a position ; whilst in 

 others, it might be conceded by most persons that these beds 

 of conglomerate have not undergone any movement since 

 their formation. Now, in the former instances, can it be 

 maintained that the inclined planes, traversing the conglome- 

 rate, are always referrible to the lines of horizontal stratifica- 

 tion ? In the last chapter we answered this in the negative, 

 and the case now before us strengthens this decision. 



Thus Lyell *, in describing the inclined layers which occur 

 between horizontal ones in the crag formation of Suffolk, 

 and which are disposed at angles of 30 and even 45, says 

 that " this diagonal arrangement of the layers, sometimes 



* Principles of Geology, vol. iii. p. 174. 



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