File:Manganese oxide-coated chert in limestone (Lost River Chert Bed, Middle Mississippian; Martel Avenue, Mammoth Cave, Kentucky, USA) 13 (24145978758).jpg

From Wikimedia Commons, the free media repository
Jump to navigation Jump to search

Original file (4,000 × 3,000 pixels, file size: 5.04 MB, MIME type: image/jpeg)

Captions

Captions

Add a one-line explanation of what this file represents

Summary

[edit]
Description

Chert horizon in limestone in the Mississippian of Kentucky, USA.

The dark-colored, moth-eaten, ratty-looking rocks at the middle of the photo are weathered and eroded cherts. This is part of the Mississippian-aged Lost River Chert Bed, which consists of >1 horizon in a limestone succession. It is a laterally-discontinuous horizon and does not consist of discrete, subrounded chert nodules.

Chert is a cryptocrystalline, quartzose sedimentary rock. It is not readily prone to dissolution by slightly acidic groundwater, unlike limestone. In cave passages, the chert is an erosion-resistant unit and often protrudes slightly to prominently from the surrounding limestone walls.

Chert, being composed of quartz (SiO2), is hard (H = 7 on the Mohs Hardness Scale). Underground samples of Lost River Chert Bed do not have hard surfaces, however. The exposed rock in this horizon usually has a dark-colored, often black, coating of one or more manganese oxide minerals. The Mn-oxide coatings are relatively soft. The underlying chert is hard.

Stratigraphy: Lost River Chert Bed, Horse Cave Member, upper St. Louis Limestone, upper Middle Mississippian

Locality: outcrop along Martel Avenue, Mammoth Cave Ridge, Mammoth Cave National Park, western Kentucky, USA
Date
Source Manganese oxide-coated chert in limestone (Lost River Chert Bed, Middle Mississippian; Martel Avenue, Mammoth Cave, Kentucky, USA) 13
Author James St. John

Licensing

[edit]
w:en:Creative Commons
attribution
This file is licensed under the Creative Commons Attribution 2.0 Generic license.
You are free:
  • to share – to copy, distribute and transmit the work
  • to remix – to adapt the work
Under the following conditions:
  • attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
This image was originally posted to Flickr by James St. John at https://flickr.com/photos/47445767@N05/24145978758 (archive). It was reviewed on 7 December 2019 by FlickreviewR 2 and was confirmed to be licensed under the terms of the cc-by-2.0.

7 December 2019

File history

Click on a date/time to view the file as it appeared at that time.

Date/TimeThumbnailDimensionsUserComment
current18:08, 7 December 2019Thumbnail for version as of 18:08, 7 December 20194,000 × 3,000 (5.04 MB)Ser Amantio di Nicolao (talk | contribs)Transferred from Flickr via #flickr2commons

There are no pages that use this file.

Metadata