Many deposits of oxides have recently formed and are probably now forming in bogs in many regions, notably New Brunswick, Canada. They are not important as sources of production. Although no simple relation seems to govern the distribution of manganese in unweathered rock, there is reason for believing that the accumulation of manganese oxides in the weathered mantle is favored by climates that cause unusually complete or deep rock decay. Although a few manganese oxide deposits are found within the belts of recent glaciation, and some have no relation to weathering, most of the important deposits occur in areas now or recently favored with warm, humid climates, and there is reason for suspecting that such areas will yield other important deposits. GEOGRAPHICAL DISTRIBUTION =North America.=--In the United States, the occurrence of manganese ore can be most clearly described by grouping the districts according to grade or ore: (1) high grade, containing 35 per cent. or more of manganese, which is used ordinarily for making the high-grade alloy, ferromanganese, and (2) low-grade, ferruginous manganese ore, used ordinarily for the low-grade ferro-alloy, spiegeleisen. The country is deficient in natural supplies of the former, but has abundant resources of the latter, which under the stress of necessity could be largely substituted for the high-grade ore, which is now mainly imported. The following districts in the United States yield high-grade ore: At Philipsburg, Mont., are bodies of manganese carbonate that replace Cambrian limestone near veins and igneous contacts. These are weathered to oxides to a depth of about 200 feet below the surface. At Butte, Mont., veins in granite contain manganese carbonate and silicate, locally weathered to oxides. In the Shenandoah Valley in Virginia, and in similar valleys in Tennessee and Georgia, the residual clays from certain Cambrian limestones and Silurian shale and sandstone yield bodies of manganese oxides to depths that range from 200 to 250 feet below the surface. Many small deposits also occur in Arkansas, Arizona, California, Nevada, and Utah. The total production of the United States from 1838 to 1918 was 893,734 tons, and the maximum was 305,869 tons in 1918. Among the chief districts yielding the lower grade of ore (10 to 35 per cent. manganese) the most conspicuous is the Cuyuna district in Minnesota, where beds of iron-manganese carbonate of pre-Cambrian age are weathered to oxides to depths of 250 to 500 feet below the surface and contain ore bodies carrying 7 to 20 per cent. manganese, and 25 to 50 per cent. iron. The single deposits range from 50,000 to 7,500,000 tons each. Since the first shipments in 1913, the production through 1918 has been 1,666,677 tons of ore carrying more than 5 per cent. manganese.