THEORY OF THE EARTH. 421 



But there is still another difficulty, which may either 

 be a fresh one, as to a correct theory, or may possibly 

 offer the solution of the preceding facts. The " pri- 

 mary" strata having been formed, partly at least, from 

 previous stratified rocks, there oug % ht to exist masses 

 of those somewhere, not less than of the very primary 

 themselves, after the numerous revolutions which they 

 have undergone. And these should now appear to us 

 as portions of our primary strata ; yet only because 

 geologists had not formed a correct theory, from not 

 having observed and reasoned on the fragments in 

 these, and have therefore never thought of such a pos- 

 sibility. Whether they will ever be distinguished, I 

 cannot now foresee : but they ought to be similar to 

 the primary, because their fragments are so, and they 

 ought to be uucon form able ; so that the case just 

 quoted, with many more that I have observed, may be 

 the very* ante" primary" strata in question. 



This sixth earth furnishes the materials of those 

 secondary strata which precede the coal ; as the time 

 of their production, could it be ascertained, would be 

 the measure of its duration. And a third revolution 

 elevates those strata ; thus producing a new and se- 

 venth form of the earth, or a third modification of a 

 stratified one. And here we begin first to trace dis- 

 tinctly the increase in the variety of the strata ; toge- 

 ther with the continuous records of an organized cre- 

 ation. The latter quesfion I must separate and defer: 

 the former may take its place here, once for all. 



However various the primary strata may now be, 

 and however different from the secondary, I have fully 

 shown that there is a radical analogy between the two, 

 often indeed reaching to almost an identity, in every 

 thing essential ; as also, that the action of heat pro- 

 duces the same or similar changes in the secondary 



