426 Geological Inquiries, 



4. Are there any indications of its having formcriy had a dif- 

 ferent level ? 



§ VIII. Concerning Rocks. 



1 . Their horizontal outline ? 



2. Are they separated from each other by thin bands of clay, 

 or other extraneous substances ? or slightly joined to one an-. 

 other ? or firmly welded together ? 



3. When two rocks of different species come in contact, is 

 any difference in colour, hardness, &.'c. observable between the 

 adjacent surfaces and other portions of the same rock ? 



4. When a rock terminates at the surface of the earth, are 

 any fragments of it to be traced in the form of gravel, &c. ? — 

 Does it re-appear after such interruption, and what is the nature 

 of the intervening substance ? 



5. The form of their broken ends? 



6. Are any rocks observed to terminate constantly together ? 

 and what are they ? 



If Stratijied. 



7. I? the stratification distinct or indistinct ? 



8. What is the number and thickness of the strata, and the 

 order of their position ? 



9. Do they alternate or recur at regular intervals ? 



10. Do they, whether straight or waved, preserve their paral- 

 lelism throughout, or are they cuneiform, &:c. ? 



11. When vertical, what points of the compass are opposed, 

 to their sides, and what to their edges ? 



12. What is the amount of their dip, or the angle which they 

 form with the horizon? and is it the same throughout their who'.s 

 extent ? 



13. To what point of the compass do they decline ? 



14. Where several strata, of the same species, are incumbeiit 

 on each other, do they differ in thickness or consolidation ? 



15. Whdre veins, dykes, or fissures occur, are the strata de- 

 pressed, elevated, contorted, or altered in any other way ? 



16. How far does the external form of the mountain cor- 

 respond with the position of the strata ? 



17. If the stratum contains broad and thin distinct particles, 

 (such as mica) do these all lie in the same direction ? 



Note. — Care mast be taken in examining strata, not to be de- 

 ceived by distance or perspective, or by mistaking fissures for 

 stratification, and fallen strata for strata in their natural position; 

 and it should be kept in mind, that before the inclination of a 

 stratum can be determined with certainty, it is necessary that it 

 .should be seen on two of its adjacent sides. 



// 



