Among the leading facts connected with the occurrence of mineral substances and the elementary bodies on the Pacific coast, and especially in the Cordilleras of North and South America, the following may be mentioned as generally applicable to the whole of the vast region extending from British Columbia to Chile:
1st. The paucity of species considering the extent of the region as compared with other parts of the world, and especially with other mineral regions.
2d. The remarkable absence of the prominent silicates, and especially of the zeolites.
3d. The absence of a large number of the elementary substances, and the paucity of several others of very common occurrence in other mineral regions.
4th. The very wide spread and abundant occurrence of the precious metals, gold and silver, and the not uncommon occurrence of platina.
5th. The great abundance of ores of copper, and the comparative absence of tin, lead, and zinc.
6th. The similarity in the mineralized condition of the silver—antimony and chlorine being prominent mineralizers of this metal—while in Chile the rarer combinations of iodine, bromine, and selenium occur, these latter being as yet unknown north of Mexico.
7th. The absence or paucity as veinstone, or gangue, of one of the most prominent minerals occurring as such in other mineral regions, namely, fluor; to which it may be added, that both calcite and barytes are extremely rare as veinstones in California, and to judge from all the Mexican and Chilean collections that I have seen, well crystallized specimens are very rare in those countries.
8th. There is no elementary substance, and but few mineral species peculiar to the Pacific coast, so far as yet ascertained.
Professor Whitney remarked on the depression of Death Valley, the sink of the Amargosa River, below the level of the sea. Recently it has been repeatedly stated in the newspapers that no such depression really existed, and that, in point of fact, the valley in question was several thousand feet above the sea level, Mr. Gabb being cited as authority.