Sandstone Boxwork





Photo credit: Bryan Melton
Sandstone boxwork is a unusual phenomenon that we see on the margins of the Cumberland Plateau.

There are three things that must happen first to produce boxwork.
    Jointing
    Mineralization
    Weathering

Jointing

Produced in a parent rock of sandstone, this type of boxwork originates as small joints which run in a box shape. The origins of these joints could be from frost wedging - where water in the rock freezes and cracks the rock, or it could unloading pressure from the rock de-watering, or it could be from some other physical process. The origins of the boxwork joints are still a bit of a mystery.

If the following steps occur without previous jointing then one gets Liesegang Rings.

Mineralization

The joints become a place of preferential mineralization. Groundwater loaded with iron minerals moves through the pores of the sandstone. Where it finds a void, like in the joints, it tends to drop minerals out of solution. The rust colored minerals you find on your water heater at the house are chemically quite similar to this boxwork. 

Weathering

The joint surface must first be exposed to weathering, whether by cliff failure, slump, or some other wasting process. The exposed surface's sandstone weathers out first, leaving in place the mineralized boxwork. Because the sandstone around it is removed, the boxwork tends to protrude after its been well developed.

Similar Features

Boxwork is a type of Liesegang ring. Liesegang rings lack obvious structural control, as in they do not have joint influenced development.

Painted Rock, Painted Rock Cave, Big South Fork NRRA, Fenress County, Tennessee Liesegang rings, Rockcastle conglomerate, Eagle shelter, White County, Tennessee 2 Megan Atkinson, Liesegang rings, Fentress Formation, Big South Fork NRRA, Scott County, Tennessee

Comments

Post a Comment

Popular posts from this blog

Missing People Map

Image
Sometime around middle to late November of 2019, I started getting tagged in posts on Reddit and Facebook where a map purported to show a correlation between missing person cases and caves. The two maps in question were of terrible quality in both content and image quality (so very much JPG compression). Somehow these maps managed to capture the public's attention for several weeks. In fact, more than two months later I am still being asked questions about the map. What follows is a critical analysis of the maps from both a cartographer's perspective, as well as a caver's. Origin Where did each image come from that comprised the map? The top image is titled " North America Cluster Map " and is produced by the Canam Missing Project / Missing 411. I cannot comment on the methods used to produce the map since they aren't stated. For this reason I am immediately suspect that this is conveying real information. I'll touch on why the form of this ma
Read more

Jungle Book Film (1994) and the Upper Cumberland

Image
Table of Contents The Story David Starnes's Photos April Moore's Photos Watch Guide for Locals THE STORY BEHIND WALT DISNEY'S DECISION TO FILM RUDYARD KIPLING'S JUNGLE BOOK MOVIE AT LOST CREEK CAVE AND WATERFALL A PERSONAL RECOLLECTION BY DAVID STARNES RETIRED PRINCIPAL PLANNER LOCAL PLANNING ASSISTANCE OFFICE TENNESSEE DEPARTMENT OF ECONOMIC AND COMMUNITY DEVELOPMENT I was employed by the State of Tennessee as a community planner from October 1990 to August 2011. The Local Planning Assistance Office of the Upper Cumberland region was based in Cookeville. Our agency was in the Tennessee Department of Economic and Community Development, which also included the Tennessee Film Commission. Occasionally, different agencies would meet to explain their role in fostering economic growth in the state, and this was how my love for caving became entwined in the 1994 Walt Disney live-actio
Read more