. Bulletin of the Geological Society of America. Geology. Figure 1.—Sketch of Concretion in Pennsijlranian Shale in Boone County, Missouri Shows lenses of clay between the bedding planes. of lateral growth, such as crumpling of the beds, which would be neces- sary in these beds, because the concretion is not due to local cementation, as shown by the stratification planes passing over and not through them, it must be concluded that the slickensides are due to upward growth sub- sequent to deposition, or that the beds slipped down around the concretion during consolidation. CONCRETIONS IN THE CR
. Bulletin of the Geological Society of America. Geology. Figure 1.—Sketch of Concretion in Pennsijlranian Shale in Boone County, Missouri Shows lenses of clay between the bedding planes. of lateral growth, such as crumpling of the beds, which would be neces- sary in these beds, because the concretion is not due to local cementation, as shown by the stratification planes passing over and not through them, it must be concluded that the slickensides are due to upward growth sub- sequent to deposition, or that the beds slipped down around the concretion during consolidation. CONCRETIONS IN THE CRETACEOUS (GRANEROS) SHALES IN SOUTH DAKOTA AND WTOMING The lower part of the Graneros shale (Cretaceous) in the northern Black Hills contains many concretions. Some of the best of these are in Figure 2.—Sketch of Concretion in Mowry Shale near Belle Fourche, South Dakota Note horizontal stratification in the concretion and the bedding planes curving around it. the Mowry shale member. These concretions attain a length of 6 or 7 feet and a thickness of 15 to 18 inches. They are circular, elliptical, and irregular in plan and distinctly lenticular in cross-section, becoming. 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
