Ch. Yin.] OF ROCKS IX GENERAL. 91 



ceive that the terra primary must either be entirely renounced, or, if re- 

 tained, must be differently defined, and not made to designate a set of 

 crystalline rocks, some of which are already ascertained to be newer than 

 all the secondary formations. In this work I shall follow most nearly 

 the method proposed by Mr. Boue, who has called all fossiliferous rocks 

 older than the secondary by the name of primary. To prevent con- 

 fusion, I shall sometimes speak of these last as the primary fossiliferous 

 formations, because the word primary has hitherto been most generally 

 connected with the idea of a non-fossiliferous rock. Some geologists, to 

 avoid misapprehension, have introduced the term Paleozoic for primary, 

 from tfaXaiov, " ancient," and £wov, "an organic being," still retaining the 

 terms secondary and tertiary ; Mr. Phillips, for the sake of uniformity, has 

 proposed Mesozoic, for secondary, from ixstfog, " middle," &c. ; and Caino- 

 zoic, for tertiary, from xuivog, " recent," &c. ; but the terms primary, sec- 

 ondary, and tertiary are synonymous, and have the claim of priority in 

 their favor. 



If we can prove any plutonic, volcanic, or metamorphic rocks to be 

 older than the secondary formations, such rocks will also be primary, ac- 

 cording to this system. Mr. Boue, having with propriety excluded the 

 metamorphic rocks, as a class, from the primary formations, proposed to 

 call them all " crystalline schists." 



As there are secondary fossiliferous strata, so we shall find that there 

 are plutonic, volcanic, and metamorphic rocks of contemporaneous origin, 

 which I shall also term secondary. 



In the next chapter it will be shown that the strata above the chalk 

 have been called tertiary. If, therefore, we discover any volcanic, plutonic, 

 or metamorphic rocks, which have originated since the deposition of the 

 chalk, these also will rank as tertiary formations. 



It may perhaps be suggested that some metamorphic strata, and some 

 granites, may be anterior in date to the oldest of the primary fossilifer- 

 ous rocks. This opinion is doubtless true, and will be discussed in future 

 chapters ; but I may here observe, that when we arrange the four classes 

 of rocks in four parallel columns in one table of chronology, it is by no 

 means assumed that these columns are all of equal length' ; one may 

 begin at an earlier period than the rest, and another may come down to 

 a later point of time. In the small part of the globe hitherto examined, 

 it is hardly to be expected that we should have discovered either the 

 oldest or the newest members of each of the four classes of rocks. Thus, 

 if there be primary, secondary, and tertiary rocks of the aqueous or fos- 

 siliferous class, and in like manner primary, secondary, and tertiary hypo- 

 gene formations, we may not be yet acquainted with the most ancient of 

 the primary fossiliferous beds, or with the newest of the hypogene. 



