South of these mines, toward Trabuco Cañon, another claim is being worked. South of the Trabuco the conglomerates hide the lode, except at one spot, where it appears and has been worked. The Cretaceous formation grows lower as the Trabuco is approached, and does not appear prominent south of it. In all probability it is covered by the Tertiary, for the elevation and consequent erosion have not been as great in this direction. SAN BERNARDINO COUNTY. By W. H. Storms, Assistant in the Field. No portion of California has more diversified mineral wealth than the county of San Bernardino. Although its area is comprised largely of rugged mountains and desert waste, yet this county is a producer of gold, silver, copper, lead, and tin, and contains mines of zinc, iron, and manganese, besides deposits of borax, salt, soda, baryta, gypsum, sulphur, onyx, marble, asbestos, and structural material, granite, and sandstone of great beauty and value. Within its borders are found a wide range of geological formations from Paleozoic (if not Archæan) to Tertiary, and a great variety of rocks of igneous origin. The mines are scattered all over its thousands of square miles of territory, and have already added millions of dollars to the wealth of the State and the world. Many of its mines are of phenomenal richness, and were it not for the expense and extreme difficulty attending transportation in the desert, San Bernardino County would undoubtedly take first place in adding to the mineral wealth of California. The largest and most productive section in the county at present is THE CALICO MINING DISTRICT. No region affords better opportunities for the study of a certain class of ore deposits occurring in eruptive and fragmental rocks than may be found in the Calico District. The mines, condemned at first, came quickly to the front nevertheless, and have for the past twelve years been steady producers of silver bullion. The district is situated 6 miles north of the Atlantic and Pacific Railroad, the nearest station being Daggett. GENERAL GEOLOGY OF THE REGION. The geology of the Calico Mountains at first sight looks simple enough, but a more thorough investigation quickly convinced me that there were structural problems to be studied of more than passing importance, as they seemed to have a bearing upon the extent of the ore deposits. The most complex region is that immediately about the town of Calico, in the vicinity of the mines. The balance of the mountain area is more simple.