Google map with 43 deep sinkholes ( > 100')

Visual analysis -- topo reconnaissance

In the 2001 Shofner study, geology students were assigned the task of scanning the state's topo maps (7.5' quadrangles) for sinkholes (hachured contours). A grid was provided for a quadrangle, and the students counted the number of sinkhole contour lines that crossed the grid lines. So rather than just a raw count of sinkholes, the metric accounted somewhat for depth and area. Here are density maps gray scale or color from the study. We were unable to locate the raw data counts from the study.

In 2013 using javascript and on-line topos (CalTopo.com), we clicked on TN sinkholes to record lat,lon. There are over 54,000 sinkholes visible on the 800 USGS TN topo quadrangles. The Talbott quadrangle has over 1,280 sinkholes, and many more uncounted beneath Cherokee Lake. (By comparison, the Bald Knob quadrangle has the highest number of caves at 345.) Counting sinkholes from the USGS topo maps or the equivalent digital DEM data reveals only the sinkholes that were visible with the photogrammetric techniques used to process the USGS aerial photos. This simple sinkhole count does not account for sinkhole volume (area*depth), so Grassy Cove counts as 1 just like one of the teeny spot sinkholes. Also topo contour interval (10', 20', or 40') can affect the number of sinkholes noted on USGS maps -- 10' contour maps typically showing more sinkholes. Most TN quads are 20' contours.

There are many more (5 times?) sinkholes than the 54,000 recorded by the USGS photogrammetric technigues. In hiking karstic areas, you will find many sinkholes that don't show on the USGS topo maps. Ongoing LiDAR aerial surveys should provide more detailed topographic data, 2013-16 surveys.
See various sinkholes per quadrangle maps below:

• google map graduated circles
• sinkhole heatmap (or heatmap using 3x3 subdivison of quad)
• choropleth quads (or color cells using 3x3 subdivison of quad)
• ESRI map of US karst areas with big TN sinkholes and sinks/quad
• pins on all Anderson county sinkholes, zoom and view with topo map layer (e.g. CalTopo)
• view 10m DEM elevation tick marks overlaid on deep sinkhole on google map or on Big Sink
• lat,lon sinkhole data quad files tnsinksq.zip 54,000+ lat,lon pairs (1MB)

Quadrangle	Sinkholes
Talbott	1284
Verona	1124
Sango	920
Springfield North	907
Livingston	896
Unionville	829
Vine	819
Sparta	813

513 of the state's 803 7.5' quads have at least one sinkhole (64%). 85 of the state's 95 counties have at least one sinkhole (89%). If we refine the data by dividing each quad into a 3x3 grid, then about 30% of the state's 7,227 cells have at least one sinkhole. As an example of the sinkhole clustering, see the Anderson county sinkholes.

Digital analysis 2013

Chuck Sutherland located Tennessee sinkholes in the USGS 10m DEM digital elevation data (2013) using Spatial Analyst with ArcMap. The nominal accuracy of USGS topo elevation data is half the contour-interval. Most of Tennessee topos use 20' contour, so the digital analysis summarized here only considers sinkholes with a depth of at least 3m. The ArcMap analysis provides sinkhole location (boundary path), area, perimeter, depth, and volume.

The raw data located 21,365 sinkholes (or depressions) with a depth of at least 3m. It is necessary to review the raw data and remove false sinkholes ("fauxholes"). Outliers include man-made depressions (quarries, gravel pits, clay pits, strip-mine holding ponds, levees, road impoundments) and non-karst depressions such as stream-channel depressions and depressions in the sandy soils of west Tennessee. There were also digital anomalies at some quad boundaries, perhaps, reflecting older DEM data based on 7.5' quadrangles. At least 15.4% of the data were false sinkholes -- scrubbing is ongoing.

County	Sinkholes	DEM 3m+
Robertson	3,602	861
Montgomery	3,025	900
Rutherford	2,988	572
White	2,970	1,070
Jefferson	2,364	773

Not surprisingly, the spatial correlation coefficent is 0.93 for sinkholes per quad for the scrubbed DEM data versus the visual counts per quad (54,0000+). The table at right shows that counties with the most sinkholes have a slightly different order if only sinkholes of depth 3m or more are counted from the DEM data. For all sinkholes, Robertson County had 3,602, but for depths of at least 3m, White county has the most. A table at the bottom of the page show the regional distribution of sinkholes and caves.

Similary, the underlying sinkholes per quad are roughly the same. For all sinkholes visible on topo, the Talbott quadrangle has the highest count at 1,284, but for DEM sinkholes with a depth of at least 3m, the Livingston quad has the highest (391) and Talbott is second (383). (Based on scrubbed 3m+ DEM data). The CDF shows the density of sinkholes (caves) per quad -- 36% of the quads have no visual sinkholes, 42% have no sinkholes of depth 3m+, and 43% have no caves. To see differences in detail of visual analysis sinkholes (black pin) versus the 3m+ DEM sinkholes (red circle) view the Anderson county data, topo sinkholes. There were 625 visual sinkholes on topo map, and the digital analysis reported 239 sinkholes of depth 3m or more (288 unscrubbed). The spatial distribution of visual vs digital sinkholes over Anderson county is roughly the same (hence the high spatial correlation).

The scrollable table below lists caves and sinkholes per county and the sinkholes of distinction for each county -- deepest, largest area, largest volume. The last four columns are based on the digital analysis of sinkholes with a depth of at least 3m (scrubbed data).

The table at right shows the number of topo sinkholes in a few metropolitan areas. A Cookeville 2009 sinkhole floodplain report based on LiDAR found 217 sinkholes (our topo count is 52, 27 for 3m+). Chuck Sutherland's Sparta analysis using 2017 TN LiDAR elevation data. For a coarser state-wide view, see choropleth map and zoom in using topo base map (Caltopo) to see topo sinkholes.

Here are various Google maps of digital analysis for sinkholes with depth of 3m+ on 3x3 grid over 7.5' topo quad. Each cell is 2.5'x2.5' equivalent to the Shofner block.

• choropleth sinkhole count map or heatmap
• choropleth sinkhole depth map or heatmap, metric is sum of sinkhole depths in cell
• choropleth sinkhole area map or heatmap, metric is sum of sinkhole areas in cell
• choropleth sinkhole volume map or heatmap, metric is sum of sinkhole volumes in cell
• if we subtract out digital sinkholes (3m+) from visual count, we're left with this map of shallow visual sinkholes 36,299 shallow sinkholes (heatmap)
• Anderson County sinkholes map visual (black pins) and 3m+ (red circles)

The following tables summarize the 3m+ digital data and give the top 10 sinkholes in volume and area.

Sinkhole depth
The following table shows the distribution of depth or greater over the collection of sinkholes.

Depth (ft)	Sinkholes	raw
3m+	18,081	21,365
10'	17,522	20,519
20'	7,058	7,977
30'	2,771	3,152
40'	1,195	1,361
50'	569	664
100'	41	53
200'	3	4

The raw data reported 53 deep-hole candidates, but 10 of those were quarries and two were road impoundments. The 43 deepest sinkholes are listed in the table at the top of the page (list sorted by depth). The cumulative distribution show that 50% of the sinkholes have a depth of 16' or less and 95% have a depth of 44' or less. Our visual analysis would suggest there are 36,000+ sinkholes with a depth less than 3m (map). If we had digital data for sinkholes less than 3m, then our CDF's would have a different shape.

Sinkhole area
The following table lists the 10 biggest sinkholes by area (minimum depth 3m).

Sinkhole	Area (km2)
Grassy Cove	13.6
Collier	4.9
Sinking Cove	4.5
Burtons	4.2
Old Zion	3.5
Lost Creek	3.5
Byler Bottoms	3.3
Walnut Grove	2.9
Lake Karen	2.7
Fort Campbell	2.7

Some of the sinkholes above do not show an enclosing sinkhole contour on the topo maps, but the digital analysis provides the coordinates for the enclosing path (for example, see Collier). Spatial Analyst seems to underestimate size of Northcutts Cove sinkhole???

The following table shows the cumulative distribution of area over the collection of 3m+ sinkholes (raw and scrubbed data).

Area (km2)	Sinkholes	raw
0.0006	18,026	21,150
0.001	17,774	20,754
0.01	8,215	9,703
0.1	907	1,152
1	40	53
10	1	1

Sinkhole volume
The following table lists the 10 biggest sinkholes by volume.

Sinkhole	Volume (106m3)
Grassy Cove	37.3
Icy Cove	8.5
Sinking Cove	4.3
Lost Creek	4.0
The Big Sink	4.0
Big Sink	3.2
Big(gest) Sink	3.1
Cane Hollow	3.0
Lake Karen	2.5
Round Cove	2.4

The following table lists the counties with the largest cumulative volume of sinkholes.

County	104m3
Cumberland	4071
White	3874
Putnam	1972
Warren	1891
Franklin	1776
Overton	1730
Montgomery	1631

The following table lists the USGS 7.5' topo quadrangles with the largest cumulative volume of sinkholes.

quad	104m3
Grassy Cove	4009
Monterey Lake	1173
Doyle	1125
Dry Valley	881
Cardwell Mountain	829

See sinkholes per quadrangle chloropleth map

visiting sinkholes

Most of the Tennessee sinkholes are on private property, but you can visit the following:

• drive thru Grassy Cove or Sinking Cove
• Norris watershed, Eli Nine Sinkholes Trail, only one of the sinkholes shows on topo, hiking GPS track
• Loyston Point trails Hemlock Bluff, Norris Lake
• Cedars of Lebanon State Park 35+ sinkholes along Hidden Springs Trail
• Dodson sinkhole Falls
• Panther Creek state park seven sinkholes trail
• Sinkhole trail in Knoxville's Hastie Park
• Sinkhole Crest Trail in Oak Ridge at UT arboretum
• Sinkhole trail in Oak Ridge North Bounday greenway
• Haw Ridge Park small to tiny
• Wilderness Trail in Murfreesboro's Barfield Crescent Park
• Hickory Ridge Nature Loop in Henry Horton State Park
• Three Hickories Trail along Percy Priest Lake
• Inland Trail in Long Hunter State Park
• Cookeville's Ensor Sink Natural Area 36.150598,-85.505225
• sinkholes along Tellico's East Lakeshore Trail
• sinkholes along Black Mountain section of Cumberland Trail
• sinkholes in Chuck Swan WMA Union County's deepest sinkhole 36.324493,-83.956961
• two deep sinkholes in the Great Smoky Mountains National Park
• Icy Cove
• scenic Shortfoot's Natural Bridge over sinkhole pond in Monroe County
• Virgin Falls comes out of a cave and drops into a sinkhole

Spatial density of Tennessee sinkholes and caves

County	Sinkholes	Caves
Anderson	625	63
Davidson	609	87
Hamilton	531	84
Jefferson	2,364	103
Knox	1,663	167
Marshall	2,312	44
Montgomery	3,025	81
Robertson	3,602	162
Van Buren	653	836
White	2,970	1,169
see ESRI map

The Tennessee Cave Society (TCS) has coordinates for the state's 11,283caves (2020), site includes cave-density map and caves per county. Using Sutherland's cumulative data for caves-per-county and caves-per-quadrangle, we can compare topo sinkhole and cave density. (The 2001 Shofner study also compared cave and sinkhole density.) The table at right highlights the county cave and sinkhole density (see full table above) and the following maps illustrate the density.

• caves-per-county map 2017 or 2013 or 2012 or 2011 (courtesy Chuck Sutherland)
• ESRI caves/county (2012) map graduated circles with sinkholes/county
• 2013 caves per quad Google choropleth map or Google graduated circles map or Google heatmap
• Sutherland's 2013 cave and sinkhole density map based on 3m+ deep sinkholes weighted by volume
• 2001 Shofner density maps

The Shofner paper reports spatial correlation (0.20) between caves and sinkholes. Using our sinkholes/quad count (visual analysis) and TCS caves/quad count, we calculate a spatial correlation of 0.35 for the whole state. The spatial correlation drops to 0.30 if we exclude quads with no caves and no sinkholes. The correlation of caves to sinkholes of 3m+ depth (digital analysis) is 0.26. About 36% of the state 7.5' quads and 10 of the 95 counties have no caves and no sinkholes.

Notable public caves Lost Sea, Ruby Falls, Dunbar Cave, Bell Witch Cave, Big Bone Cave, Cumblerland Caverns, Tuckaleechee Caverns, Raccoon Mountain Caverns, and Forbidden Caverns. Blue Spring Cave is the most extensive TN cave (35 miles).

Caves and surface geology:

Additional information

• Google map/image/topo with deep sinkholes and elevation query tools
• leafletjs (non-google) TN sinkholes map
• TN physiography or geologic map of Tennessee

  Regional sinkhole distribution

  Region	Sinkholes	DEM 3m+	Caves
  Western	<1%	<1%	<1%
  Highland Rim W	14%	11%	7%
  Central Basin	22%	15%	11%
  Highland Rim E	15%	16%	33%
  Plateau	4%	6%	31%
  Valley	42%	50%	16%
  Mountains	1%	1%	2%

• more about TN sinkholes
• Shofner paper on TN sinkhole index and gray-scale sinkhole density map 2001
• another TN sinkhole and cave distribution based on Shofner data (color maps)
• Using GIS to identify sinkholes 2011
• karst subsidence in East TN 1988
• Unicoi county sinkhole
• Clarksville karst and I24 sinkhole and 2014 Austin-Peay sinkhole and earthcache urban sinkhole
• Knoxville, James White Parkway TDOT 2008 karst study and 2013 karst study
• Knoxville Karst Hydrogeology of the Ten Mile Creek Watershed 2009
• Knox county sinkhole drainage basins 1973
• Cookeville sinkhole floodplain report 2009 (LiDAR), 217 sinkholes (our topo count is 52, 27 3m+)
• Chuck's LiDAR analysis Sparta, TN 2017
• Karst aquiefers in Tennessee
• more TN geology info
• Tennessee Topography, bulletin #86, David Starnes, 2009
• USGS US sinkholes with karst map and 2004 USA karst map another US cave/karst map or US cave density
• Appalachian karst map cave density, 2005
• Using LiDAR to map sinkholes W Va 2008, 33 sinkholes, my visual USGS scan shows 56
• LiDAR and sinkhole plain of Illinois 2012
• wikipedia sinkhole info and how sinkholes work or USGS science of sinkholes
• Kentucky sinkholes
  • GIS shapefiles 107,176 sinkholes, area but no depth data, largest area: 7,724 acres, area CDF
  • KY karst map
  • Coincidence between sinkholes and geologic structure KY
  • KY sinkholes cross-section
  • KY groundwater resoures by county, karst map
• sinkhole info for NC or AL and here or PA sinkhole map or VA sinkholes and ESRI map
• Illinois county sinkholes examples of old aerial photos of sinkholes (1940)
• sinkhole density Columbia quadrangle Illinois, highest density: 135/sq mile
• LiDAR in Tennessee map and 2014-2018 LiDAR survey business plan and technical specs (18 cm veritcal RMSE)
• TN 2013-16 LiDAR surveys
• using LiDAR to map WV sinkholes and LiDAR and Smokies sinkholes
• Iowa lidar sinkhole mapping 2012
• An Evaluation of Automated GIS Tools for Delineating Karst Sinkholes and Closed Depressions from 1-meter LiDAR-derived Digital Elevation Data
• TN GIS ecoregions ESRI map
• urban sinkholes
• Tennessee-Georgia-Alabama (TAG region) cave density
• USGS National Elevation Dataset NED
• Andy's US big hole list and on Google map and list with lat/lon and see Saline Valley an endorheic basin
• US lowpoint guide
• world's largest sinkholes/depressions and Mexico's deepest water-filled sinkhole and Belize Great Blue Hole 1000 feet across and more than 400 feet deep
• China sinkholes
• deepest lakes
• Yahoo prominence forum and subsidence and prominence/basin theory
• anti-prominence sinkholes, basins greater than 300', US map
• TN county high points
• TN topo maps by county and state-wide index (pdf) and alphabetical or here

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   © Tom Dunigan
Revised Mon, 09 Sep 2024 04:52:34 -0600