Dead Man’s Hole, as it would be baptized, was discovered in 1821 by Ferdinand Leuders, an entomologist observing nocturnal insects. He recorded his findings without taking much note of the geological phenomenon that would become a notorious burial ground following the Civil War where it would be used to dispose of the bodies of murdered and lynched men for ideological reasons.
A sinkhole is a natural hole that forms in the Earth's surface as a result of the chemical weathering of carbonate rocks like limestone, a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate (CaCO3). Many limestone rocks are composed from skeletal fragments of marine organisms such as coral or foraminifera. Limestone makes up about 10% of the total volume of all sedimentary rocks. The solubility of limestone in water and weak acid solutions leads to karst landscapes, in which water erodes the white limestone over thousands to millions of years. Most cave systems are through limestone bedrock.
Sinkholes may vary in size from 1 to 600 m (3.3 to 2,000 ft.) both in diameter and depth, and vary in form from water weathered soil-lined bowls to chemical erosion of limestone rock by nature gases bedrock-edged chasms, such as the Dead Man’s Hole. Sinkholes are frequently linked with karst landscapes. The type of landscape made up of these rocks is known as karst topography. In such regions, there may be a few or even thousands of sinkholes in a small area so that the surface if seen from the air looks pock-marked, and there are no surface streams because all drainage occurs subsurface. Sinkholes may be formed gradually or suddenly depending on natural water-drainage patterns.
Sinkholes that form in thick layers of homogeneous limestone, facilitated by high groundwater flow, such as heavy rainfall can create bedrock-edged chasms. Some sinkholes form when the land surface is changed, such as industrial or heavy agriculture demands on the top soil are created such as over grazing, losing valuable topsoil, allowing weathering to occur to the exposed bedrock. *Note, sinkholes may also form in high and dry places in certain locations due to the chemical weathering of nature gases that escape from underground pockets. The formation of sinkholes involves natural processes of erosion or gradual removal of slightly soluble bedrock (such as limestone) by percolating water, the collapse of a cave roof, or a lowering of the water table. Occasionally a sinkhole may exhibit a visible opening into a cave below.
The well-like hole, located in southern Burnet County, Texas is believed to be caused when the rock below the land surface (limestone) was naturally dissolved by water and a buildup of natural gas pressure. As the rock dissolves, a space developed underground. These sinkholes can be dramatic, because the surface land usually stays intact until there is not enough support. Then, a sudden collapse of the land surface or pressurize gas eruption (blow out) can occur such as Dead Man’s Hole which is small compared to others, measuring around 7 feet in diameter at the surface, but has a cavernous depth of about 15 stories. The presence of gas however prevented extensive exploration, until the gas evidently dissipated over time. Then in 1951, a group of spelunkers from the University of Texas successfully descended the hole. They reported that Dead Man's Hole was seven feet in diameter at the surface and about 160 feet deep; at its base, the hole split into two "arms," one extending straight back for about fifteen feet, and the other sloping downward at a 45° angle for about thirty feet.
In 1997, Ona Lou Roper, owner of the property, donated 6.53 acres, which included Dead Man's Hole, to Burnet County. It was declared a Texas Historical Site the next year. Even though the opening is closed by a metal grate, the surrounding rock structure is worth checking out.
To claim this earthcache email me the answers to the questions
Q1. According to the Texas Historical Marker at this location, how big is Dead Man’s Hole?
Q2. What type of bedrock surrounds the opening and what color is it after scratching.
Q3. What was the primary cause to the creation of this geological feature?
Q4. Is Dead Man’s Hole a cave or sinkhole? What is the reason for your answer?
CONGRATULATIONS!!! Going out to HiDude_98 for FTF! You Rock Man! No pun intended...