Iron Oxide Needles

Iron Oxide Needles
Iron Oxide Needles

NPS Photo by Art Palmer

1st Trip: On 4/13/2003, Rod Horrocks led Dan Wray and Tim Moreland to the Amphitheater in the Historic Section where they discovered some black filamental iron fixing bacterial strands.

Trip Report: We went to the CM2 survey off the Amphitheater to start surveying the numerous leads that we found on a previous survey to the area. Starting at CM2R, we surveyed south into a virgin crawl. However, it reconnected to the CM2 survey after seven shots. We then went up to CM12E and surveyed SW past a rock covered with specimens collected in the 1890's and connected to station CM9. After shooting a shot into a dead-end room from CM8, we surveyed NW from CM8 towards a large blank area on the map. A choked passage continued west, but the main passage turned NE. This virgin passage has some nice mud crack curl ups. We mapped up a couple of parallel passages with the CM survey, tying into the C' survey at C18. We noticed that the CM and the C' surveys are actually in the same passage. I'll have to deal with this latter. We then surveyed up into a dome, where we connected to NB27. We ran out of time at this point. We surveyed 461 feet and left numerous leads along most of our surveys. Needs another trip.

P.S: At CM8, we found some very strange things. There is a small patch of black needles hanging straight down, about 1/2" in length. They look like an upside down pin cushion. Some of the larger needles, 1 1/2", have some web-like filamental loops and connections between them. Very interesting looking.

Bed of Nails Speleothems
Bed of Nails Speleothems

NPS Photo by Bill Holmes

2nd Trip: On 6/20/2003, Rod Horrocks led Art & Peg Palmer, Philippe Audra, & Philipp Hauselmann to the Amphitheater area in the Historic Section to look at the black needles found on 4/13/03.

Trip Report: I led a group of speleologists (Art & Peg Palmer) to an area I had helped survey on 4/13/03, just NE of the Amphitheater; where iron-oxide-rich filaments were displayed in a paleo-pocket. These filaments are up to 2 cm long and are jet black, except for a filigree of gray web-like filaments in places (probably calcite coated). The black filaments are essentially vertical and hang down from the ceiling of the paleo-pocket, which has been exposed in the cave by the dropping away of the walls of the pocket. The filaments are about half a millimeter in diameter. Some are tipped by a small white bulb-like mineral growth, most likely an evaporite mineral such as hydromagnesite. We also looked at iron oxide pseudomorphs after pyrite that were exposed in some nearby proto pockets.

Art Palmer Note:These filaments probably date to before the paleo-fill, so they are Mississippian in age. They relate to a period of oxidation that also formed many of the yellow and brown crystals nearby. These filaments are uncoated, which is very rare. On most places they have a calcite coating (Bed of Nails) or quartz coating (Crown Jewels). Each of these coatings dates from the period of deep burial (probably Mesozoic Period), showing the antiquity of the filaments. No samples were taken.

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Last updated: April 10, 2015

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