In general all these changes of the deeper zone tend to make the rocks more crystalline and dense and to make the minerals more complex. Cavities are closed. The process is in the main an integrating and constructive one which has been called _anamorphism_, to contrast it with the disintegrating and destructive processes near the surface, which have been called _katamorphism_ (see also pp. 27-28). There is little in the process of anamorphism in the way of sorting and segregation which tends to enrich and concentrate the metallic ore bodies. On the contrary the process tends to lock up the valuable minerals in resistant combinations with other substances, making them more difficult to recover in mining. Later igneous intrusions or the ordinary ground-waters may bring in minerals which locally enrich ores under anamorphic conditions, but these are relatively minor effects. An illustration of the general effect is afforded by a comparison of the Cuban iron ores, which are soft and can be easily taken out, with the Cle Elum iron ores of Washington, which seem to be of much the same origin, but which have subsequently been buried by other rocks and rendered hard and crystalline. In the first case the ores can be mined easily and cheaply with steam shovels at the surface. In the second, underground methods of mining are required, which cost too much for the grade of ore recovered. On the other hand, the same general kind of anamorphic processes, when applied to coal, result in concentration and improvement of grade. The same is true up to a certain point in the concentration of oil; but where the process goes too far, the oil may be lost (pp. 140-141). CONCLUSION Mineral deposits are formed and modified by practically all known geologic processes, but looked at broadly the main values are produced in three principal ways: (1) As after effects of igneous intrusion, through the agency of aqueous and gaseous solutions given off from the cooling magma. (2) Through the sorting processes of sedimentation,--the same processes which form sandstone, shale, and limestone. Organic agencies are important factors in these processes. (3) Through weathering of the rock surface in place, which may develop values either by dissolving out the valuable minerals and redepositing them in concentrated form, or by dissolving out the non-valuable minerals and leaving the valuable minerals concentrated in place. The latter process is by far the more important. The overwhelming preponderance of values of mineral deposits as a whole is found in the second of the classes named.