File:Lava flows capping North Table Mountain & South Table Mountain (Denver Formation, Upper Cretaceous; Golden, Colorado, USA).jpg

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English: The topographic highs along the horizon are North Table Mountain (left & center) and South Table Mountain (right) in Golden, Colorado. The stratigraphic section at Table Mountain consists of the Denver Formation (latest Cretaceous to earliest Tertiary), a siliciclastics-dominated succession with shale, siltstone, and occasional coarser-grained beds like conglomerate, deposited at a time of low relief. Rocky Mountains uplift and deformation had not yet reached this area at that time. The overlying unit is the Green Mountain Conglomerate, which was deposited near some local relief, probably from movement along the Golden Fault.

The cliff-forming unit at the top of Table Mountain consists of lava flows. Four flows occur in the section - flow # 3 and flow # 4 occur in the top cliff. Flow # 1 forms a minor cliff below that. Flow # 2 only occurs on one side of Table Mountain. Flows # 1 and 2 were small-volume, channel-filling lava flows. The lava flows are composed of porphyritic shoshonite, which is a splitter's term for potassic basalt. The lava flows date to 63-64 Ma, during the late Maastrichtian. All four flows together are about 0.75 cubic kilometers in volume. Northwest of North Table Mountain is the vent area, consisting of two nested plugs - Ralston Dike is the larger of the two.

Based on Denver Formation fossils, this area was probably a savannah during the latest Cretaceous, perhaps with patches of jungle growth.

In the bottom foreground are ~vertically-oriented, sandstone horizons of the Upper Cretaceous Laramie Formation.

Locality: view of North Table Mountain & South Table Mountain from Parfet Prehistoric Preserve in the town of Golden, north-central Colorado, USA
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Source https://www.flickr.com/photos/47445767@N05/52744003368/
Author James St. John

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This file is licensed under the Creative Commons Attribution 2.0 Generic license.
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This image was originally posted to Flickr by James St. John at https://flickr.com/photos/47445767@N05/52744003368. It was reviewed on 13 March 2023 by FlickreviewR 2 and was confirmed to be licensed under the terms of the cc-by-2.0.

13 March 2023

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current03:25, 13 March 2023Thumbnail for version as of 03:25, 13 March 20233,006 × 1,622 (4.36 MB)Ser Amantio di Nicolao (talk | contribs)Uploaded a work by James St. John from https://www.flickr.com/photos/47445767@N05/52744003368/ with UploadWizard

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