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| [CHAPTER I.] OF THE MATERIAL WHICH COMPOSE THE CRUST OF THE EARTH. | |
| [SECTION I.]—ELEMENTARY SUBSTANCES, | 11 |
| [SECTION II.]—SIMPLE MINERALS, | 13 |
| [SECTION III.]—THE MINERAL MASSES WHICH FORM THE CRUST OF THE EARTH, | 16 |
| [CHAPTER II.] OF THE ARRANGEMENT OF THE MATERIALS WHICH COMPOSE THE CRUST OF THE EARTH. | |
| [SECTION I.]—THE CLASSIFICATION OF ROCKS, | 21 |
| [SECTION II.]—THE PLUTONIC ROCKS, | 23 |
| [SECTION III.]—THE VOLCANIC ROCKS, | 25 |
| [SECTION IV.]—THE NON-FOSSILIFEROUS STRATIFIED (OR METAMORPHIC) ROCKS, | 30 |
| [SECTION V.]—THE FOSSILIFEROUS ROCKS, | 32 |
| [SECTION VI.]—FOSSILS, | 57 |
| [SECTION VII.]—THE TIME NECESSARY FOR THE FORMATION OF THE STRATIFIED ROCKS, | 63 |
| [CHAPTER III.] OF THE CHANGES TO WHICH THE CRUST OF THE EARTH HAS BEEN SUBJECTED. | |
| [SECTION I.]—CHANGES WHICH HAVE TAKEN PLACE AT GREAT DEPTHS BELOW THE SURFACE, | 67 |
| [SECTION II.]—CHANGES IN THE MASS OF THE STRATIFIED ROCKS, | 68 |
| [SECTION III.]—CHANGES OF ELEVATION AND SUBSIDENCE, | 73 |
| [SECTION IV.]—CHANGES ON THE SURFACE OF THE EARTH, | 85 |
| [SECTION V.]—CHANGES OF CLIMATE, | 88 |
| [SECTION VI.]—ADVANTAGES RESULTING FROM GEOLOGICAL CHANGES, | 91 |
| [CHAPTER IV.] OF THE CAUSES OF GEOLOGICAL PHENOMENA. | |
| [SECTION I.]—ATMOSPHERIC CAUSES, | 95 |
| [SECTION II.]—CHEMICAL ACTION, | 97 |
| [SECTION III.]—ORGANIC CAUSES, | 101 |
| [SECTION IV.]—AQUEOUS CAUSES, | 103 |
| [SECTION V.]—AQUEO-GLACIAL ACTION, | 120 |
| [SECTION VI.]—IGNEOUS CAUSES, | 127 |
CHAPTER I.
OF THE MATERIALS WHICH COMPOSE THE CRUST OF THE EARTH.
SECTION I.—ELEMENTARY SUBSTANCES.
There are about sixty substances known to the chemist which are considered as elementary; but most of them are rarely met with, and only in minute quantities. A few of them are, however, so abundant, in the composition of the crust of the earth, as to render some attention to them necessary.
Oxygen is more widely diffused than any other substance. It is an ingredient of water and of the atmosphere, the former containing eighty-eight per cent., and the latter twenty-one. Nearly all rocks contain oxygen in combination with the metallic and metalloid bases, and the average proportion of oxygen which they contain is about forty-five per cent.; so that it will not differ much from the truth to consider the oxygen in the earth’s crust as equal in weight to all the other substances which enter into its composition.
Hydrogen occurs in nature principally in combination with oxygen, forming water. It is also an ingredient in bitumen and bituminous coal.
Nitrogen is confined almost entirely to the atmosphere, of which it forms four-fifths. It enters into the composition of some varieties of coal, and is sparingly diffused in most fossiliferous rocks.
One of the most important substances in nature is carbon. It constitutes the principal part of all the varieties of coal, as well as of graphite, peat and bituminous matter. A much larger amount of carbon exists in the carbonic acid which is combined with the oxides of the metalloids and metals. The most abundant of these compounds is limestone, which contains about twelve per cent, of carbon.