DIY History | Transcribe | Scholarship at Iowa | Coal Measures and Coal Mining in Iowa, including paleontology and a discussion on the coal formation; also the methods of mining by Russell T. Hartman, 1898 | Coal Measures and Coal Mining in Iowa by Russell T. Hartman, 1898, Page 151

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Coal Measures and Coal Mining in Iowa, including paleontology and a discussion on the coal formation; also the methods of mining by Russell T. Hartman, 1898

Coal Measures and Coal Mining in Iowa by Russell T. Hartman, 1898, Page 151

[page]150.[/page]

both above and below concavity deeper below than above. Periphery slightly convex, rather broad, a distinct ridge or carina at both upper and lower borders; upper ridge more acute than lower, regularly crenate or [?subuodose?], projecting nearly upward, while the lower ridge is slightly rounded and projects outward and downward. Volutions five or six in number. Surface marked by well defined lines of growth. On the upper side these lines start perpendicularly from the sutures and past these about half way across the [??] about half way across the volutions, thence they turn backward until near the upper carina which they cross in a perpendicular direction; on the periphery these lines curve forward for about one third the distance across, then turn backward, crossing the lower carina at

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[page]150.[/page] both above and below concavity deeper below than above. Periphery slightly convex, rather broad, a distinct ridge or carina at both upper and lower borders; upper ridge more acute than lower, regularly crenate or [?subuodose?], projecting nearly upward, while the lower ridge is slightly rounded and projects outward and downward. Volutions five or six in number. Surface marked by well defined lines of growth. On the upper side these lines start perpendicularly from the sutures and past these about half way across the [??] about half way across the volutions, thence they turn backward until near the upper carina which they cross in a perpendicular direction; on the periphery these lines curve forward for about one third the distance across, then turn backward, crossing the lower carina at