Cobble with cemented pebbles-granules-sand from a lithic conglomerate (Quaternary; Rt. 715 roadcut, just east of the Knox County-Coshocton County line, Ohio, USA) 8 : 無料・フリー素材/写真
Cobble with cemented pebbles-granules-sand from a lithic conglomerate (Quaternary; Rt. 715 roadcut, just east of the Knox County-Coshocton County line, Ohio, USA) 8 / James St. John
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
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| 説明 | Cobble eroded from a conglomerate in the Quaternary of Ohio, USA.I came across an outcrop of conglomerate on a recent field trip. It was odd, however - it was a lithic conglomerate, with multicolored gravel of varying rock types. Eastern Ohio only has quartz-pebble conglomerates - lithic conglomerates are not present. Float samples and outcrop at this locality had an odd, irregular, "punky" weathering style, indicating the conglomerate was incompletely cemented/lithified. After considering the hypothesis that this was old concrete ("rockus fakus"), it was concluded that this was a natural occurrence of lithic conglomerate. It is not part of eastern Ohio's bedrock, however - it is a partially lithified Quaternary fluvial terrace deposit. In other words, this is a gravel deposit from a post-glaciation river. The outcrop occurs on the northern margin of a moderately large river valley. The modern river channel is small compared with the size of the valley (= an underfit stream). During post-glaciation melting, the river valley was high-flow with a high sediment load.Cross-bedding is visible in outcrop and in float material. Graded bedding is also present - the conglomerate grades to sandstone in places. Most of the conglomerate clasts are pebble-sized, but cobbles were also observed (see above photo). Cross-bedded conglomerate is a stereotypical lithology in fluvial (river) facies.Age: post-Wisconsinan, ~latest Pleistocene or early HoloceneLocality: roadcut on the northern side of Rt. 715 (= Walhonding Road), just east of the Knox County-Coshocton County line, northern margin of the Kokosing River Valley, eastern Ohio, USA (~40° 22’ 29.44” North latitude, ~82° 11’ 14.74” West longitude) |
| 撮影日 | 2017-02-19 15:09:47 |
| 撮影者 | James St. John |
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