Ironstone concretion (lower Pottsville Group, Lower Pennsylvanian; Pleasant Valley Limestone Quarry, Muskingum County, Ohio, USA) 3 : 無料・フリー素材/写真
Ironstone concretion (lower Pottsville Group, Lower Pennsylvanian; Pleasant Valley Limestone Quarry, Muskingum County, Ohio, USA) 3 / James St. John
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
|---|---|
| 説明 | Ironstone concretion from the Pennsylvanian of Ohio, USA. (millimeter scale)This concretion is from a quarry in western Muskingum County, Ohio. The quarry targets Maxville Limestone and crushes it for use as road gravel, fill, rip-rap, and erosion-control blocks. The Maxville here is an erosional outlier that is described in Stout (1918).Lithologically, the specimen is ironstone. Apparent carbonized fossil plant material is present on the surface, plus possible fault slickenlines (click on the photo to zoom in).The stratigraphy at this quarry includes basal Pennsylvanian sedimentary rocks disconformably overlying Mississippian Maxville Limestone:1) ~4 to 5 feet of fissile black shale with smooth, slightly shiny concretions (paleopebbles?)2) Sharon Conglomerate - quartz-pebble conglomerate3) Black shale4) Gray, non-fissile claystone with lumpy iron oxide concretions5) Unconformity with minor paleotopography6) Maxville Limestone - mostly lime mudstone (micritic limestone) with occasional lenses or pockets of fossil shell hash; some thin shale interbeds; one small apparent sandstone lens (= relatively thin, gray, clay-rich interval with sandy-silty grains); occasional coarsely-crystalline/coarse-grained limestone intervals with finely laminated argillaceous limestone; some slickenlined surfaces seen in the incompetent clay-rich intervals. Observed fossils include brachiopods (Composita subquadrata atrypids), bivalves, gastropods (Straparollus planodorsatus and Bellerophon sublaevis), and crinoids (even calyx material). Straparollus gastropods are common in the argillaceous intervals - they are compacted and compressed. One Straparollus fossil snail was seen with a healed shell fracture/break.Notable Pennsylvanian float samples in the section: a Lepidodendron tree trunk with nice, diamond-shaped leaf scars and a coarse-grained, rip-up clast breccia.Stratigraphy: black shale interval in the lower Pottsville Group (about 10 feet above the Maxville-Pottsville disconformity), upper Lower PennsylvanianLocality: Pleasant Valley Limestone Quarry, southwest of Dillon Lake, Hopewell Township, western Muskingum County, eastern Ohio, USA (~vicinity of 39° 58' 49.64" North latitude, 82° 08' 05.74" West longitude)-------------------------Reference cited:Stout (1918) - Geology of Muskingum County. Geological Survey of Ohio, Fourth Series, Bulletin 21. 351 pp. |
| 撮影日 | 2018-10-03 17:18:08 |
| 撮影者 | James St. John |
| タグ | |
| 撮影地 |