42 Dr. Mac Culloch on 



many works otherwise valuable ; since nothing but minute 

 and careful details of the connexions of the rocks described 

 in them, can enable us to translate them into a meaning. 

 Among the works of those who use names instead of descrip- 

 tions, it would be quite fruitless to seek for one ; and it is per- 

 haps the safest practice to avoid those in which the term 

 transition occupies this prominent place. 



I may now venture to examine the objections which apply 

 to the ancient division into primitive and secondary, as well 

 as those which may be made to that method of arrangement, 

 under certain modifications. It will be seen that the latter is 

 free from some of those which apply to the former. I need 

 not dwell on the objections that first meet the view in the 

 ancient arrangement, namely, the confounding of granite and 

 trap with the stratified rocks. With respect to the stratified, 

 it is by no means true that, in the primitive class, they are 

 necessarily placed at high angles. On the contrary, they are 

 found at every angle, even down to the horizontal, though it 

 may be admitted that angles exceeding 15° are more common 

 than small ones. In the same way, so far are the secondary 

 rocks from being necessarily horizontal, or placed at low angles, 

 that they present the utmost variety in this respect. The first 

 member of this class, the red sandstone, is frequently elevated 

 to very high angles ; the coal strata are noted for their irregu- 

 larity, and even chalk has been found in a vertical position. 



It is further supposed, in this ancient division into primitive 

 and secondary, that a consecutive order, or common paral- 

 lelism, exists in each class ; and that this order in the one is 

 not consecutive to that of the other, has been more than once 

 noticed. It is thus supposed that a general disturbance or 

 elevation of the primitive strata took place before the deposi- 

 tion of the secondary, and that these also were all deposited 

 under another period of repose. Now it is very well known 

 that, in the secondary class, there are abundant proofs of 

 changes of position, and that there are in it breaches of the 

 parallel consecutive order. 



The conclusion to be drawn from these objections is obvious. 

 The arrangement, even into two classes, ought to be considered 

 an artificial, not a natural one ; and those characters which 



