1813.] 



On Veins, 



S51 



into four distinct classes, beginning with the lowest, and termi- 

 nating with the highest. To these classes he has given the name 

 of formations. They are as Bllows : — 



I. Primitive Formations, 



Principal, 



1. Granite. 



2. Gneiss. 



3. Mica slate. 



4. Clay slate. 



12. Newer porphyry. 



13. Syenite. 



14. Newer serpentine. 



1. Grey wacke. 



2. Transition lii 



1. Old red sandstone. 



2. First floetz limestone. 



3. First floetz gypsum. 



4. Variegated sandstone. 



5. Second floetz gypsum. 



6. Second floetz, or shell 



limestone. 



Subordinate. 



5. Older porphyry. 



6. Primitive trap. 



7. Primitive limestone, 

 i 8. Older serpentine. 



9. Quartz. 

 10. Gypsum. 

 " ^11. Older flinty slate. 



trap. 



flinty slate. 



7. Third sandstone, or free- 



stone. 



8. Chalk. 



9. Independent coal. 

 10. Floetz trap. 



II. Transition Formations. 



3. Transition 

 mestone. 4, Transition 



III. Floetz Formations, 



IV. Allmnal Formations, 



Sand, gravel, &c. 



Loam. 



Clay. 



Turf, &c. 



These rocks are sometimes composed of immense blocks, some- 

 times of regular layers placed one above the other. When these 

 layers consist of repetitions of the same kind of rock, they are 

 called strata ; when they consist of difl:erent kinds of rock, they 

 are called beds. The position of these strata and beds is very 

 various. In some cases they are nearly vertical; in others, 

 perfectly horizontal; and they are to be found at all angles 

 between the vertical and horizontal. 



Besides these rocks there is another species of solid matter 

 which frequently occurs in the earth, small indeed in point of 

 quantity, but of the utmost importance in a mineralogical point 



