. Bulletin of the Geological Society of America. Geology. RELATION OF CALCITE AND DOLOMITE 447 A few miles northeast of Sylacauga, where the field narrows and is bordered on either side by parallel ridges, the following section (figure 13) is approximately correct: n. w. „ / s. E. So°. Figure 13.—Section through Marlle Valley at right Angles to the Strike Phyllite similar to that on east side. i!. White marble, with opening of Alabama Marble Quarries Company here. Talladega phyllite RELATION OF CALCITE AND DOLOMITE 111 many parts of the field the calcite marble is interbedded with dolo- mite.
. Bulletin of the Geological Society of America. Geology. RELATION OF CALCITE AND DOLOMITE 447 A few miles northeast of Sylacauga, where the field narrows and is bordered on either side by parallel ridges, the following section (figure 13) is approximately correct: n. w. „ / s. E. So°. Figure 13.—Section through Marlle Valley at right Angles to the Strike Phyllite similar to that on east side. i!. White marble, with opening of Alabama Marble Quarries Company here. Talladega phyllite RELATION OF CALCITE AND DOLOMITE 111 many parts of the field the calcite marble is interbedded with dolo- mite. The line between these two minerals is a very sharp one, as is shown by the study of thin rock sections taken through the contact. Fre- quently there is a thin film of iron ox id? separating the two minerals. This interbedding of dolomite and calcite has been observed in the Knox Dolomite formation, which lies to the west of the main marble belt for a considerable portion of the field. Frequently these beds are very thin. The following section (figure 14) is taken from an outcrop in a sink about three miles southwest of Gantts Quarry and illus- trates on a small scale what takes place in thicker beds elsewhere in the field. It is evident from the sharp line between the calcite and the dolomite that there must have been a difference in the character of the originally deposited materials in these beds. Whether this difference was physical or chemical cannot be told from the present investigation; but if there was not an original deposition of dolomite the mineral originally occupying the place of the dolomite was exclusively favored in the replacement process. CHARACTERISTICS OF THE MARBLE The Alabama marble is usually described as a fine-grained white mar- ble. It exhibits more or less chloritic and talcose veining and clouding. DOLOM/T£ MARBLE 6 OOLOM/r£ MARBLE «? DOLOM/rE MAXBL£ 3' DOLO/1/TE Figure 14. — Section from the Knox Dolomite Area jwst to the west of the ma
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectgeology, bookyear1890
