. Underground water resources of Iowa . sands and gravels of the driftunderlying the city may be pure and wholesome, but they should belooked upon with suspicion because of the ease of surface and sewer 726 TJK&EilGSOlTiTD WATEfi HESOUSCES Of IOWA. contamination and should be used only after bacteriologic examination by competent authority. Such wells in rural regions are gener-ally wholesome if properly guarded at the surface. All of the water obtained above the rock contains some carbonateof iron, which, on standing, oxidizes to the brown hydrated oxide ofiron, and the water becomes milky an
. Underground water resources of Iowa . sands and gravels of the driftunderlying the city may be pure and wholesome, but they should belooked upon with suspicion because of the ease of surface and sewer 726 TJK&EilGSOlTiTD WATEfi HESOUSCES Of IOWA. contamination and should be used only after bacteriologic examination by competent authority. Such wells in rural regions are gener-ally wholesome if properly guarded at the surface. All of the water obtained above the rock contains some carbonateof iron, which, on standing, oxidizes to the brown hydrated oxide ofiron, and the water becomes milky and precipitates a brownish sedi-ment. In all large supplies this may be removed by aeration, andfor domestic use on a small scale it is not objectionable except to theesthetic sense. A prospect hole for coal and gas, drilled on the bank of Iowa Rivernear Marshalltown (W. * NW. J sec. 25), has a depth of 1,020 curb is about 885 feet above sea level. Record of strata in jprospect hole at Marshalltown {PI. XI, p. 382). Carboniferous (Mississippian): Kinderhook group (320 feet tliick; top, 885 feet above sea level)— Limestone, light ; in fine sand; many angular fragments of limpid quartz at 68 feet Limestone, light yellow, compact, earthy luster; 3 samples Limestone, brown, crystalline, cherty atll5 feet Shale, soft, light-green, calcareous Devonian (300 feet thick; top, 505 feet above sea level): Limestone (?); no samples Limestone, hard, brovv-n-gray, and brown; crystalline; rapid effervescence; sam-ples at 465 and 560 feet Silurian (305 feet thick; top, 265 feet above sea level): Dolomite, yellow, gypseous and cherty 55 675 Limestone, magnesian, brown, three samples; cherty at 675 feet 95 770 Dolomite, cherty, gypseous; mostly of white and translucent chert 30 800 Chert, white and translucent,at 800 No samples 75 875 Limestone; rapid effervescence; drillings almost wholly chert; some gypsum; 2 samples 40 915 Dolomite, white, in powder; some chert and gypsu
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Keywords: ., bookcentury1900, bookdecade, booksubjectwatersupply, bookyear1912
