Vertically-oriented beds of the Laramie Formation (Upper Cretaceous; Parfet Prehistoric Preserve, Golden, Colorado, USA) 77 : 無料・フリー素材/写真
Vertically-oriented beds of the Laramie Formation (Upper Cretaceous; Parfet Prehistoric Preserve, Golden, Colorado, USA) 77 / 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 | This is the site of an old clay mining operation in Golden, Colorado. Soft clay horizons occurred between hard sandstone intervals of the Laramie Formation. The beds here are vertically oriented - structural tilting occurred during the Laramide Orogeny in the Tertiary. The Laramie Formation is a nonmarine, coastal plain to deltaic succession of mostly mixed siliciclastic sedimentary rocks - sandstones, siltstones, claystones, and coals.After clay mining ceased, the site became a landfill for ash from coal burning operations. Landfill activity buried many dinosaur footprints preserved in the Laramie Formation sandstones. The locality is now a "fossil preserve" with dinosaur footprints, plant fossils, and other features that can be closely examined along trails. An odd-looking golf course makes up the rest of the old clay mine.-----------------------------------Two versions of on-site signage:Clay MiningSince 1877, five generations of the Parfet Family have mined clay from this area. Previously operated as the Parfet Clay Pit, the ceramic and brick industry used clay from this area primarily for bricks and sewer pipe. The Governor’s mansion, East and South High Schools in Denver, and the Jefferson County Hall of Justice in Golden were built from the distinctive tan bricks.The clay, deposited in lakes and swamps 68 million years ago during the Late Cretaceous, is part of the Laramie Formation. Uplift of the modern day Rocky Mountains some 67-55 million years ago tilted the rock strata to their near vertical position. The clay layers were excavataed as trenches, leaving the vertical fins of sandstone visible today. Trace fossils such as dinosaur tracks and leaf impressions are visible on many of the remaining sandstone walls. The pits on either side of the trail contain fossil footprints that have yet to be detailed.Logs, wedged horizontally between the sandstone walls, served as a warning device to miners. If the walls started to give way, the miners would hear the logs creak or “sing” and move to safety.-----------------------Clay MiningClay from the Fossil Trace Golf Course, previously operated as the Parfet Clay Pits, has been mined for the ceramic and brick industries since 1877 by five generations of the Parfet family. The predominant uses of this clay were for brick and sewer pipe. The tan brick was used to build the Governor’s mansion, East and South High Schools in Denver and the Jefferson County Hall of Justice in Golden. The clay was deposited in small ponds and depressions about 70 million years ago in the Late Cretaceous period and became part of the Laramie Formation. The rock strata were tilted vertical by the uplift of the modern day Rocky Mountains to the west approximately 60-65 million years ago. Clay layers were excavated as trenches, leaving vertical fins of sandstone, which contain trace fossils. The sandstone was originally sand which was deposited when adjacent streams overflowed their banks during flood events.-----------------------------------Stratigraphy: Laramie Formation, Maastrichtian Stage, upper Upper CretaceousLocality: outcrops at Parfet Prehistoric Preserve, southern side of the town of Golden, Colorado, USA |
| 撮影日 | 2007-07-25 16:11:47 |
| 撮影者 | James St. John |
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