. Bulletin of the Geological Society of America. Geology. Figure 6.—Section of the Oolitic Iron Ores of the Lower Siluric (2) resting discon- formaoly on Haquoketa Shales. Iron Ridge, Wisconsin region. The absence of Juniata and Bald Eagle beds in eastern Penn- sylvania, where they must have existed, since the material of which they are composed could only have been derived from the old land still farther to the east, is explained by the fact that the Taconic folding carried the bottoms of the synclines above the present erosion plane. When it is remembered that these folds were truncated, and
. Bulletin of the Geological Society of America. Geology. Figure 6.—Section of the Oolitic Iron Ores of the Lower Siluric (2) resting discon- formaoly on Haquoketa Shales. Iron Ridge, Wisconsin region. The absence of Juniata and Bald Eagle beds in eastern Penn- sylvania, where they must have existed, since the material of which they are composed could only have been derived from the old land still farther to the east, is explained by the fact that the Taconic folding carried the bottoms of the synclines above the present erosion plane. When it is remembered that these folds were truncated, and that the region was essentially peneplaned in early Mesozoic time, and that, finally, Tertiary. Figure 7.—Cross-secticn of the Iran Deposit at Iron Ridge, Wisconsin 1. Maquoketa shale, marked at the top by a layer of polished pebbles ; 2, cross-bedded oolitic iron ore ; 3, Maysville limestone erosion has affected primarily this eastern belt, it is not surprising that all vestiges of the former eastward extent of these formations have been removed. If we consider that the first effect of folding in this region was to throw the red Juniata beds into relief, and with these the underlying white Bald Eagle quartzites, we are compelled to recognize that the first fruit of subsequent erosion would be an abundance of red (or highly oxydized) material, followed by white quartzitic material, when the axes. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Geological Society of America. [New York : The Society]
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectgeology, bookyear1890
