. Transactions. contact between the monzonite andthe limestones being practically vertical. I have indicated on theaccompanying sketch map the general conditions. The specific fact I wish to bring out for the attention of those inter-ested in the discussion on The Origin of the Garnet Zones and AssociatedOre Deposits,^ by Waldemar Lindgren, and Recrystallization of Lime- 2 Trans., xlviii, 201 to 208 (1914). 316 THE PACIFIC COAST IRON SITUATION stone at Igneous Contacts,^ by C. K. Leith, is the different alterationssustained by the same series of limestones in adjacent areas in contactwith the
. Transactions. contact between the monzonite andthe limestones being practically vertical. I have indicated on theaccompanying sketch map the general conditions. The specific fact I wish to bring out for the attention of those inter-ested in the discussion on The Origin of the Garnet Zones and AssociatedOre Deposits,^ by Waldemar Lindgren, and Recrystallization of Lime- 2 Trans., xlviii, 201 to 208 (1914). 316 THE PACIFIC COAST IRON SITUATION stone at Igneous Contacts,^ by C. K. Leith, is the different alterationssustained by the same series of limestones in adjacent areas in contactwith the same igneous intrusive rock mass. In the sketch map, I have indicated conditions 9 miles southeastof Kelso. R is the central core of this part of the Providence Mountains,composed of rhyolite, and detached small rhyolite exposures are shownat several places in the limestones marked R. XF is the line of contactbetween the sedimentary series and the quartz-monzonite mass. ^ (ijoOO j Fountain PeakK h ,. ^ ^ ° 7 .. I Miles to Kelao Scale Jffoosh lOOO aOOO Keel Fig. 1.—Sketch Map Showing Geological Conditions in Eastern San Ber-nardino County, Cal. The contact of the monzonite, cutting sharply the practically hori-zontal beds of limestone, runs for a distance of about 4 miles. BC is avertical dike of rhyolite porphyry, 100 ft. thick, an offshoot from thecentral core. The point marked A seems to have been the center ofactivitj, resulting in a replacement of the limestone by iron, over anarea of four acres, with smaller orebodies along the contact to the eastand with a great dissemination of grains and irregular replacements ofiron ore in the limestones. The original bedding planes of the limestoneare still preserved in the beds of iron ore; and in the area ABC the lime-stones have largely lost their bedded structure and a mass of crystallinedolomite or dolomitic marble has resulted. A fuller description of thegeologic features is given in my article in the Engineering and MiningJo
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Keywords: ., bo, bookcentury1800, bookdecade1870, booksubjectmineralindustries
