400 NATURAL HISTORY. 



SECOND CLASS. MASSIF OR IGXEOUS ROCKS. 



FIRST ORDER : Primitive Mountains. Stratified. 

 SECOND ORDER : Basaltic or Volcanic Rock Formations.* 



of volcanic heat, the strata thus formed have been elevated from the 

 bottom of the ocean to occupy the situations under which they now 

 appear. Thus the strata are thrown into different degrees of inclina- 

 tion to the horizon, or are broken and dislocated, or appear in nearly 

 a vertical position, depending on the degree of force or the power of 

 its application. Sometimes when the heat has been most intense, an 

 entire fusion of the materials has been effected. The rocks which 

 are not stratified, or not composed of layers, as granite, are supposed 

 to have undergone complete fusion, while those which consist of lay- 

 ers, as mica slate, are supposed to have been softened by the heat. 

 BRAXDE'S OUTLINES OF GEOLOGY. Tr. 



* The most simple division of rocks is into Primitive or Primary, 

 and Secondary. The first consisting of those which are supposed to 

 have been originally formed, such as granite and its associates, and 

 the second such as were formed by the disintegration or destruction 

 of these. In the first kind no organic remains, as plants or shells, 

 are found, and hence they are supposed to have been formed before 

 the creation of organized beings. In the Secondary, these remains 

 often exist in great abundance. To this classification the celebrated 

 Werner added the Transition Class, wliich consists of the larger 

 fragments of the Primitive, and which is intermediate between this 

 and that usually called Secondary. The following classification is 

 perhaps the simplest, and being without minute subdivisions, will be 

 most easily understood : 



. I. Primary. 



II. Transition or Intermediate. 

 III. Comprising, 

 a. The Lower Secondary Series. 

 6. The Upper Secondary Series. 

 IV. Tertiary. 



V. Basaltic and Volcanic Rocks. 

 VI Diluvial and Alluvial Deposits. 



