Iron ores, salt and sandstones . ules 4 Shaly limestone in nodules 4 Blue calcareous shales 5 Shaly sandstone 0 4 to 6 Blue or greenish sandstone 3 Greenish or blue sandstone 4 Greenish or blue sandstone 4 6 Buff sandstone 7 The whole overlying formation increases in thickness asfollowed to the west, reaching 30 feet, and the stone has a pro-nounced dip to the west. The sandstone splits readily, but isa hard rock and breaks more irregular across the bedding. The joint planes run N 300 W and N 500 E. Some irreg-ular fractures run N 200 W. One smooth fissure open for awidth of three inches runs
Iron ores, salt and sandstones . ules 4 Shaly limestone in nodules 4 Blue calcareous shales 5 Shaly sandstone 0 4 to 6 Blue or greenish sandstone 3 Greenish or blue sandstone 4 Greenish or blue sandstone 4 6 Buff sandstone 7 The whole overlying formation increases in thickness asfollowed to the west, reaching 30 feet, and the stone has a pro-nounced dip to the west. The sandstone splits readily, but isa hard rock and breaks more irregular across the bedding. The joint planes run N 300 W and N 500 E. Some irreg-ular fractures run N 200 W. One smooth fissure open for awidth of three inches runs N 300 W, but on the opposite wallit starts at an angle of N 500 W, and farther in is again N300 W. The planes N 300 W are one to eight feet apart, whilethose running N 500 E are one to five feet apart. The physical tests on this stone are given in chapterXXVI. Microscopical Structure. Mr. S. L. Powell gives the fol-lowing report on a thin section of the Sewickley sandstonefrom the Watson quarry: This rock is a heterogeneous mix-. WEST VIRGINIA GEOLOGICAL SURVEY. 461 ture of quartz grains and feldspar (orthoclase and plagioclase)in nearly equal proportions. The other original constituentsare kaolin, mica, and a few zircon crystals. In addition,.thereare a number of minerals which are evidently of secondary de-velopment ; such as silica, calcite, kaolinite, chlorite, epidote,muscovite or sericite, and iron oxide. These minerals aremostly alteration products of the original minerals notedabove, together with other ferromagnesian constituents in altprobability originally present. These secondary minerals have so intergrown as to forma compact matrix or cement for the remaining original miner-als. The quartz grains possess a very irregular outline dueto secondary enlargement by silica. Some of the feldsparsare fresh and clear, while others are either kaolinized or com-pletely altered. The average diameter of the quartz grains isabout millimeter. UPPER PITTSBURG SANDSTONE. Dr. I
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