. Bulletins of American paleontology. Devonian Rugose Corals of Iowa: Sorauf 15. Text-figure 6.—Shell Rock Formation on east wall of Tom Williams Quarry, Locality 16 (Appendix), with almost complete section of Mason City Member forming cliff overlain by slope forming Rock Grove Formation above, which is in turn overlain by the lower biostrome of the Nora Member at the top. Photograph taken in 1967. extending south and southwest of the Winnebago Riv- er, from Owen Grove on the west (Text-fig. 16) to Rockford on the east (Text-fig. 17). To the west and northwest of Owen Grove, the dominant facie
. Bulletins of American paleontology. Devonian Rugose Corals of Iowa: Sorauf 15. Text-figure 6.—Shell Rock Formation on east wall of Tom Williams Quarry, Locality 16 (Appendix), with almost complete section of Mason City Member forming cliff overlain by slope forming Rock Grove Formation above, which is in turn overlain by the lower biostrome of the Nora Member at the top. Photograph taken in 1967. extending south and southwest of the Winnebago Riv- er, from Owen Grove on the west (Text-fig. 16) to Rockford on the east (Text-fig. 17). To the west and northwest of Owen Grove, the dominant facies of the sequence is dolomitic, so that when the unit was seen at Mason City, all fossils were preserved as molds, and are not of interest for study of coral faunas. The stratigraphic sequence reported by Fenton and Fenton (1924, p. 8) is superficially biostratigraphic, al- though not in a modem sense, as presented below un- der the heading of biostratigraphy. Fenton and Fenton divided the Cerro Gordo Member (or substage as they called it) into an upper ''Spirifer zone" and a lower "striatula zone". These are traceable lithic units. Each of their "zones" was divided into a series of "fau- nules", some restricted to a single layer, {, the Lep- #9 Nora Springs #17 Baumgardner's Mil #23 Marble Rock #22 Roseville. 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 Paleontological Research Institution (Ithaca, N. Y. ); Columbia University. Ithaca, N. Y. , Paleontological Research Institution [etc. ]
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