Fig. 31. BASALTIC CAUSEWAY OF THE RIVER VOLANT. (PEP. ARDECHE, FRAKCE.) 



THE CRUST OF THE EARTH; 



OR, FIRST NOTIONS OF GEOLOGY. 

 CHAPTEE I. 



1. The earth, a subject of long-continued observation and investigation. 

 2. Mathematical geography. 3. Physical geography. 4. Phenomena 

 of the oceans and seas included in it. 5. Hydrology, meteorology, 

 and climatology. 6. Political geography. 7. General subject of 

 geography. 8. Geology. 9. Original fluidity of the eai'th inferred 

 from its sphei-oidal form. 10. This form ascertained by observation 

 and measurement. 11. The solid crust was formed while the earth was 

 in a state of rotation. 12. Increase of temperature from surface down- 

 wards. 13. Within the crust the earth still in a state of fusion. 14. 

 Subject of geology. 15. How the structure of the crust to a great depth 

 is rendered manifest. 16. Section of the crust where no disturbance 

 has taken place strata occur in a fixed order. 17. Rocks in their 

 geological sense. 18. Their classification in five principal divisions. 

 19. Lowest bed, being the foundation of the crust, consists of igneous 

 rocks produced by the superficial cooling of the molten materials of the 

 globe. 20. Materials of which the igneous rocks are formed. 21. 

 Constituents of granite, feldspar, mica, quartz. 22. These components 

 of igneous rocks agglomerated mechanically. 23. But the components 

 themselves are chemical compounds. 24. Varieties of granite 

 porphyry. 25. Gneiss. 26. Secondary rocks. 27. Transition or 

 metainorphic rocks. 28. Stratification. 29. Produced by aqueous 



LARDNER'S MUSEUM OF SCIENCE. D 33 



No. 132. 



