The Saltville Fault EarthCache
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You are in the great outdoors. Children and pets should be closely supervised for their own safety. Your search will be along a highway right of way. At Stage 2, I would park opposite the shher cliff which is the fault due to possibly falling rocks.
Millions of years ago this area was a shallow inland salt water sea. Over time many geographic changes were happening to the planet. The continents were separating, mountains were rising from the flat land or sea, and other geographical changes were occurring. What caused the mountains and hills to come up from the shallow sea that once covered this area? It is none other than the Saltville Fault.
What exactly is a fault? In geology, faults are cracks or breaks in the Earth's crust that are the result of differential motion within the crust. Faults are the source of many earthquakes that are caused by slippage vertically or laterally along the fault. The largest examples are at tectonic plate boundaries, but many small faults are known to exist that are far from active plate boundaries. The two sides of a fault are called the hanging wall and footwall. By definition, the fault always dips away from the footwall. Faults can be categorized into three groups: normal faults, transform (or strike-slip) faults and reverse (or thrust) faults. A normal fault occurs when the crust is in tension. The hanging wall moves downwards relative to the footwall. In a reverse or thrust fault, the crust is in tension and the hanging wall moves upwards in relation to the footwall. Strike-slip faults have a different type of movement than normal and reverse faults. The movement is along a horizontal plane instead of vertical.
The Saltville fault spans for over 450 miles from Craig County, VA to Alabama. Within the area you are visiting, the area is underlain by the Maccrady Formation of Mississippian age. This formation is some 350 million years old. The Mississippian strata are part of a large regional structure known as the Greendale syncline with the southeastern portion of this feature being overturned and dipping toward the southeast into Alabama. Within this overturned portion of the Maccrady Formation, we find the highest concentration of salt, gypsum, and anhydrite, which have been commercially exploited since the late 1700s and early 1800s. It was this formation that gave this town it’s namesake, SALTville. The overturning we find here was caused by the thrusting of Cambrian limestone, dolostone, shale, and sandstone over the younger Mississippian rocks in the syncline. Throughout the town the fault crops out along the base of the hills created by the Cambrian rocks in the hanging wall of the fault.
Logging requirements: While at N 36 52.808 W 081 45.361 you will notice some boulders that have been forced from the ground below. The highway was recently paved here because of damage from this fault. I was informed by the town’s tourism director the far edge of the highway was over a foot higher than the near edge. Although it is once again level, over time the same damage will surely happen again because of the fault. 1) Post a photo of you or your caching group including your gps with the larger boulder behind you. 2) E-mail me the following information for this site: the composition of the rock in the area and the condition (levelness) of the highway which undergoes constant damage due to the fault.
Next you will travel to route 91 towards Glade Spring. At N 36 51.744 W 081..47.169 you will be at a large cut which towers over the highway. Take a close look at the rock face of the cliff before you. Logging requirements: E-mail me the following information: 1) identify any rock types or minerals that you might recognize 2) post a photo of yourself and gps with the fault behind you.
I would like to send out a big thank you to Harry R. Haynes Manager of the Museum of the Middle Appalachians for the time he spent educating me on the historic town of Saltville, VA and also Charlie Bill Totten Director of Tourism for Saltville for the time he spent in showing me various features of the fault first hand. Without the time and knowledge these fine men spent educating me, this and other Saltville caches would not have be possible.
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