Sinkholes and Karst Topography Are a Clear Indication That ________

Sinkholes and Cavern Collapse

karst topography (in gray) is common in the Valley and Ridge physiographic province, only absent-minded on the Appalachian Plateau
Sectionalization of Geology and Mineral Resource (DGMR) Flexviewer page

As the groundwater dissolves limestone, it creates voids and removes the rock that supports the surface. At the ground surface, sinkholes form where the ground has subsided underneath Some valleys have no “leave” where a stream leads to a river. Instead, the h2o drains into the sinkhole, enters the cave, so exits the cave at a spring earlier reaching the river.

Luray Caverns is surrounded by sinkholes and karst landscape features
Source: Virginia Department of Conservation and Recreation, Virginia Natural Heritage Information Explorer

Some surface streams also lose water to a subsurface conduit, and can even appear to dry upwardly before reaching a river. A archetype “losing stream” is Sinking Creek in Giles County. Most of the water in the stream sinks underground about a mile before the stream reaches the New River, leaving a rocky streambed at the mouth of the creek that is filled with water only during storms.

sinkholes (shaded yellow) are clear signs of karst topography – as are creeks that lose water hush-hush and sink out of sight
Source: U.s. Geological Survey (USGS), Eggleston 7.5×7.five topographic quadrangle (2013)

The term
karst topography
describes the landforms in a region with a large number of caves, sinkholes, and losing streams. USGS quad maps apply hatched contour lines to point sinkholes, and cavers advisedly explore karst areas in hopes of discovering an entrance to a previously-undiscovered cavern.

karst topography (colored night red) is common virtually Pembroke (Giles County)
Source: US Geological Survey (USGS), Map showing surficial and generalized bedrock geology and accompanying side-looking airborne radar image of the Radford 30′ X 60′ quadrangle, Virginia and Due west Virginia

At Pembroke (downstream of Blacksburg on the New River), one caver has noticed that the contour lines showed where Fiddling Stony Creek one time emptied into the New River downstream of its current location. After closely assessing the map and looking at the site on the basis, he concluded that a big cave is probably located there, just it would require a massive excavation try to dig out an archway.

potential location of cave system with no surface opening, near Pembroke (Giles Canton)
Source: U.s. Geological Survey (USGS), Pearisburg 7.5×7.5 topographic quadrangle (2013)

area in yellow indicates sinkholes, beneath which may lie an undiscovered cave system
Source: The states Geological Survey (USGS), Pearisburg 7.5×7.5 topographic quadrangle (2013)

Near all caves show signs of rockfalls from ceilings, and a cave room may abound then large that information technology collapses. Female parent Nature does not excavate rooms according to the aforementioned engineering science designs used by coal miners, leaving pillars to back up the roof.

Natural Tunnel and Natural Bridge show what happens when simply a portion of the roof collapses. Natural Chimneys was formed by erosion of the limestone ceiling and one side of a former cavern.

The general dominion is that limestone caves are located near the surface, in the superlative i,000 anxiety. The acidic h2o is full-bodied there. By the time the surface water reaches a deeper depth, it has been neutralized and is no longer able to dissolve calcium carbonate. In New Mexico, nevertheless, some very deep caves have been formed by acid fumes ascension upwardly from underground gas deposits, and so at that place is an exception to every rule.

Limestone in Loudoun Canton – rare location for karst topography east of the Blue Ridge
Source: “Loudoun County Limestone Map” in Loudoun County’s
Individual Water Wells in Limestone Geology Regions: Frequently Asked Questions

Proposed Limestone Overlay District in Loudoun County – zoning controls based on geology
Source: Loudoun County Mapping Organisation

Caves and Springs in Virginia
Natural Span
Virginia Places