The Tiptonville Dome Earthcache EarthCache

The Tiptonville Dome is the area between the red line (the Reelfoot Fault) and the blue line (St Johns Fault) in the picture above. Reelfoot Lake is in lower right, formed when the area at left end of lake (between the two faults) was raised 15-30 feet by an earthquake uplift. The lake area has dropped as much as 20 feet. Imagine the area between the two lines uplifted, while the areas to the left of the blue line and the area right of the red line lowered. There was not near as much movement to the left of the blue line as there was to the right of the red line which formed Reelfoot Lake. Quakes in centuries prior to 1811-12 probably caused some of the uplift and drop but the quake in 1812 was the one that caused enough rise in the Tiptonville area and drop in the lake area to form the lake.

This rise between the faults caused temporary river waterfalls where the Mississippi ran backwards during 1811-12 earthquakes. It happened early on Feb. 7, 1812, when a thrust fault created a sudden dam several feet high in the bottom of the river loop near New Madrid.

The main section of river that reversed direction was from island 10 northward about 10 miles to island 8. It lasted for a few hours, though the new dams/waterfalls lasted for a few days, and ruined several flatboats.

There are three basic types of earthquake faults. The descriptions are as follows…

Dip-slip faults have walls that move up or down. That means that at the fault is either pushed together (a reverse dip-slip fault) or it is pulled apart (a normal dip-slip fault). A dip-slip fault has a hanging wall and a footwall. A normal dip-slip fault’s hanging wall slips down the footwall as the fault is pulled apart. A reverse dip-slip fault’s hanging wall slips up the footwall as the fault is pushed together.

Strike-slip faults have walls that move sideways, not up or down. That is, the slip occurs along the strike, not up or down the dip. In these faults the fault plane is usually vertical, so there is no hanging wall or footwall. The forces creating these faults are lateral or horizontal, carrying the sides past each other.

The last is called an oblique-slip fault. It has characteristics of both the dip-sip and the strike-slip faults all rolled into one. Because most faults have movement in both directions, both directions of slip must be measurable to be labeled an oblique-slip fault.

Knowing that the area called the Tiptonville dome has been raised as a result of earthquakes one would easily conclude that we are dealing with dip-slip faults here. The disappointing fact is that at this time none of the faults in the area are visible and are deep under ground. This being said the coords above will take you to a bench mark in the lawn of the Court House in Tiptonville. This bench mark disk was placed to record the elevation at that point on earth but also records the elevation at that point in time as it is inevitable that someday this “dome” will rise again!

To prove you visited this site post a picture of you and your GPSr at the benchmark when you log your find and to show the educational value of this earthcache email me the answer to the question below and your result of the required activity.

According to the wikipedia page about earth quake faults the name of the Tiptonville dome could be put another way. What other word could replace “dome” in describing the area between the two faults that was raised.

Record the elevation of the bench mark by placing your GPSr on the benchmark with the elevation page showing. Then take a close up picture so that you can read the elevation.