4 EXPLANATION OF PLATE I. 



Strata, are represented as occurring on each side of this ele- 

 vated Granite, which is supposed to have broken through, 

 and to have carried up with it to their present elevated and 

 highly inclined position, strata that were once continuous and 

 nearly horizontal.* 



The general history of Elevation appears to be, that 

 mountain chains of various extent, and various directions, 

 have been formed at irregular intervals, during the deposi- 

 tion of stratified rocks of every age; and that Granite had, 

 in many cases, acquired a state of solidity before the period 

 of its elevation. 



Within the primary Granite, we find other forms of Gra- 

 nitic matter, (a. 9.) which appear to have been intruded in 

 a state of fusion, not only into fissures of the older Granite, 

 but frequently also into the Primary stratified rocks in con- 

 tact with it, and occasionally into strata of the Transition 

 and Secondary series, (a. 10. a. 11.) these Granitic injec- 

 tions were probably in many cases, contemporaneous with 

 the elevation of the rocks they intersect ; they usually as- 

 sume the Condition of Veins, terminating upwards in small 

 branches; and vary in dimensions, from less than an inch, 

 to an indefinite width. The direction of these veins is very 

 irregular : they sometimes traverse the Primary strata at 

 right angles to their planes of stratification, at other times 

 they are protruded in a direction parallel to these planes, 

 and assume the form of beds. Some of the relations of these 

 Granitic Veins to the rocks intersected by them are repre- 

 sented at the left extremity of the Section, (a. 9.)f 



* Cases of Granite, thus elevated at a period posterior to the deposi- 

 tion of Tertiary Strata, occur in the Eastern Alps, where the Transi- 

 tion, Secondary, and Tertiary strata have all partaken of the same 

 elevation which raised the central axis of the crystalline Granitic 

 rocks. See Geol. Trans. N. S. Vol. III. PI. 36. Fig. 1. 



t In the Granite at the right extremity of the Section, the gra- 

 nitic veins are omitted, because their insertion would interfere with 



