. Bulletins of American paleontology. 22 Bulletin 355 Outcrops of the Lime Creek Formation Cerro Gordo S Floyd Counties Iowa 1 MIe J. ,#32 Bird Hill South! J I #33 Bird Hill East % ± -X Text-figure 17.—Outcrops of the Lime Creek Fomiation, largely only of the Cerro Gordo Member, except for Bird Hill, where the basal portion of the Owen Member also outcropped. The Rockford Brick and Tile Company is no longer (1997) actively quarrying the Cerro Gordo and underlying Juniper Hill Members. Further locality information is contained in the Appendix. pirifer whitneyi Zone of Day (1996). Unit 4 is
. Bulletins of American paleontology. 22 Bulletin 355 Outcrops of the Lime Creek Formation Cerro Gordo S Floyd Counties Iowa 1 MIe J. ,#32 Bird Hill South! J I #33 Bird Hill East % ± -X Text-figure 17.—Outcrops of the Lime Creek Fomiation, largely only of the Cerro Gordo Member, except for Bird Hill, where the basal portion of the Owen Member also outcropped. The Rockford Brick and Tile Company is no longer (1997) actively quarrying the Cerro Gordo and underlying Juniper Hill Members. Further locality information is contained in the Appendix. pirifer whitneyi Zone of Day (1996). Unit 4 is the Owen Member, in most part the uppermost Owen, for- merly referred to as the ''Acerxndoria zone" (Fenton and Fenton, 1924), now placed in the lowatiypa on- enensis Zone of Day (1996) on the basis of its bra- chiopod fauna. Corals are scattered throughout the Owen, especially where stromatoporoid biostromes are present, but are most abundant in the top meter of the unit. In 1989, while placing the Shell Rock Formation in the Cedar Valley Group, Witzke et al. also formally proposed the Lithograph City Formation for Cedar Valley beds that everywhere underlie the Shell Rock in north central Iowa (1989, p. 241). The understand- ing of the biostratigraphy of these Frasnian formations of Iowa has been greatly advanced by the work of Day on both conodont and brachiopod faunas of these strata from north-cenral Iowa. His summary of applicable brachiopod and conodont faunas of these beds also indicates how they are correlated with the Frasnian Composite Standard, as developed for the Montague Noire sequence by Klapper (1989). As a result of Day's work, as well as that of earlier studies, the units of the Shell Rock and Lime Creek formations have now been carefully classified by their faunas. Day summarized the ages of units in this sequence on his figure 3 (1996, ). The Shell Rock For- mation is placed in lower half of the Frasnian Stage, with all but the uppermost beds o
Size: 1836px × 1361px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorpaleontologicalresearchinstitutionit, bookcentury1900
