CHAPTER I.
ON THE DIFFERENT CLASSES OF ROCKS.
Geology defined--Successive formation of the earth's crust--Classification of rocks according to their origin and age--Aqueous rocks--Their stratification and imbedded fossils--Volcanic rocks, with and without cones and craters--Plutonic rocks, and their relation to the volcanic--Metamorphic rocks and their probable origin--The term primitive, why erroneously applied to the crystalline formations--Leading division of the work Page 1