Cumberland County Sinkhole, TN
A massive 13.31 km² depression in Tennessee’s Cumberland Plateau is North America’s largest sinkhole. It’s 140 feet deep and holds 37.7 million cubic meters of eroded limestone. Lidar surveys from 2013 confirmed it’s part of the Sequatchie Valley Anticline, a geological fold from 250 million years ago.
The sinkhole was formed by water dissolving Mississippian-era limestone bedrock. Now, underground streams drain through Mill Cave into the Sequatchie River. This maintains dynamic erosion patterns. Studies show these processes have sped up over the last 20 years.
While White County’s Big Sink is deeper at 261 feet, this Cumberland Plateau feature is wider. It’s 35.7 km around its perimeter. The anticlinal structure guides groundwater flow, creating unique karst formations in Tennessee’s eastern highlands.
Scientists use satellite imagery and cave mapping to monitor subsidence rates. These tools show how the Sequatchie Valley Anticline shapes underground drainage systems. Their research helps predict future landscape changes in active sinkhole zones.
Recent & Notable Sinkhole Incidents / Case Studies
Geological monitoring in Cumberland County TN has shown changes in sinkhole-related flooding. No big collapses have happened in Grassy Cove, but there are signs of karst hydrology risks. These risks affect drainage and farming.
Documented Sinkhole Activity (2004-Present)
Local farmers noticed water gathering in Grassy Cove fields in 2007. A 2013 study by TDEC found links between Grassy Cove Creek and the Sequatchie River. This explained why water levels changed quickly.
Wolf Cove in Franklin County is a reminder of the dangers. Its 242-foot deep sinkhole shows how fast changes can happen. Cumberland County is watching groundwater closely.
Grassy Cove Flooding Patterns & Drainage Impacts
Heavy rain turns Grassy Cove’s farmlands into lakes for 3-7 days. Records go back to 1887, when a flood lasted 11 days. Today, we see:
- Delayed planting seasons due to saturated soils
- Increased fertilizer runoff into karst aquifers
- Roadway erosion along critical drainage paths
The 2020 Hurricane Sally event showed things are getting worse. Floodwaters stayed longer than in 1994. USGS says it’s because of erosion in limestone bedrock.
Risk Factors & What Homeowners Should Do
Cumberland County TN faces special challenges because of karst subsidence. There are over 21,365 sinkholes in Tennessee that are more than three meters deep. Grassy Cove, with its farming and soft bedrock, needs extra care.
Ground-penetrating radar tests by experts are key for preventing sinkholes. These tests cost $500-$1,500, based on the property size. Regular checks on drainage systems are also important. Clear gutters and working French drains help keep water away from the ground.
Checking foundation cracks monthly is part of monitoring. The Tennessee Geological Survey says to get a pro if cracks are over 1/4 inch. Well owners should check water clarity every three months. A sudden change in water clarity might mean a sinkhole is coming.
Getting insurance that covers sinkholes is vital in risky areas. Most home insurance doesn’t cover sinkhole damage under the house. But, 42% of homes in Cumberland County now have extra coverage for earth movement.
If you see the ground sinking or buildings shifting, call the Cumberland County Emergency Management. Quick action can stop big problems. The Tennessee Geological Survey has maps and tips on their website.
FAQ
What makes Grassy Cove sinkhole geologically significant in Cumberland County?
How does Grassy Cove compare to other Tennessee sinkholes?
What evidence confirms Grassy Cove’s underground water connections?
What sinkhole risks should Cumberland County homeowners monitor?
What early warning signs indicate potentially sinkhole activity?
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