Showing posts from December, 2017

Tennessee County High and Low Points

Using quick and dirty analysis with a 10M Digital Elevation Model (DEM), I produced this dataset which shows the high and low points for each county. The highest point in Tennessee (as any native would know) is in Sevier County at Clingmans Dome, at 6644.33' The lowest point is in Davidson County at a Vulcan Materials quarry at just 90.18' above sea level. Of course, this doesn't include locations that are underground, so let's qualify that this is the lowest point that is not underground. Below is the table if you want to look at your home county. County High Point Map High Point Elevation Low Point Map Low Point Elevation Anderson 36.198101,-84.230138 3527.87 36.021527,-84.324953 757.79 Bedford 35.659490,-86.304398 1355.83 35.578287,-86.637268 630.75 Benton 35.852453,-88.206064 683.96 36.018287,-88.003935 338.01 Bledsoe 35.743564,-84.991342 2680.95 35.434861,-85.335046 707.66 Blount 35.568564,-83.70625 5526.05 35.874212,-84.009953 803.36 Bradley 3

Grassy Cove, North America's Largest Sinkhole

Grassy Cove Community Center with Brady Mountain visible behind it. Nestled in the southeastern part of Cumberland County, Tennessee lies a quiet community known as Grassy Cove. Its flat fertile land is home to agriculture and scenic farms which are still owned by the descendants of the first European inhabitants of the area. Without looking more closely at the landscape, it might escape the casual viewer that one was sitting inside a giant bowl. But with the aid of maps, it becomes readily apparent that Grassy Cove isn't like any old hollow. My first rule as a photographer/geographer is "Ask a local". Locals know a lot. For example, it's long been known that if it rains too much in Grassy Cove, then the fertile bottomland turns into a lake. It's also known from the days of yore that discarded corn shucks in the cove will appear in the Sequatchie River a few miles away, a few days later. What's going on here? Grassy Cove flooded. Structurally,

Sandstone Boxwork

Photo credit: Brian Solomon / @waterfall_hillbilly 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