What are sinkholes and there types
By Alyssa Esquivel
what is a sinkhole
A sinkhole is when it rains and the water is stuck in one area underground and drains on the surface. (''science of sinkholes'').
"Geologically, a sinkhole is a depression in the ground that has no natural external surface drainage. Basically this means that when it rains, all of the water stays inside the sinkhole and typically drains into the subsurface. Sinkholes are most common in what geologists call, “karst terrain.” What’s that? These are regions where the type of rock below the land surface can naturally be dissolved by groundwater circulating through them"
Types of sinkholes
One is based on the limestone dissolving. Another is when sand fills in the limestone that's trying to dissolve. Also there is on that's just like the previse but is based on how hard or soft it collapsed. (''sinkhole information'').
''Sinkholes can come in many different sizes and shapes. They range from shallow depressions a few inches deep and several feet across to giants that can swallow multiple houses. The sides of the sinkhole may be gently slopping or they may be vertical. There are generally three types of sinkholes.
•Limestone Solution Sinkholes – Along the western portion of Lake County, limestone is exposed at the surface or is covered by a thin layer of soil. This leaves the limestone subject to both physical and chemical processes that break down the rock. When this breakdown occurs, it usually forms a saucer or bowl-shaped depression. Due to the natural dissolving of limestone, these sinkholes develop continuously, but slowly.
•Cover-Subsidence Sinkholes – Where the sand layer may be as thick as 50 to 100 feet, with very little clay below it, the dissolving limestone is replaced by granules of sand that cascade down to fill the void. This type of sinkhole is referred to as a cover-subsidence sinkhole. These sinkholes are only a few feet in diameter and depth. Their small size is due to the fact that the cavities in the limestone cannot develop to appreciable size before they are filled with sand.
•Cover-Collapse Sinkholes – Generally, the deeper the soils, more clay is present in the soils. This clay provides some cohesiveness to the soil material above it, allowing it to bridge an existing cavity in the limestone. If this "bridge" collapses, it results in what is called a cover-collapse sinkhole. See the graphic above. The size of the sinkhole depends upon the size of the cavity. Cover collapse sinkholes form the same way as cover-subsidence sinkholes but differ mainly in the bearing strength of the soil above the cavity and whether the sinkhole subsides slowly or collapses abruptly ''
"Sinkhole Information - Water Quality Services - Environmental Utilities." Sinkhole Information - Water Quality Services - Environmental Utilities. N.p., n.d. Web. 19 May 2015.
The Science of Sinkholes. N.p., n.d. Web. 19 May 2015.