Sinkholes
What is a sinkhole?
Sinkholes are common where the rock below the land surface is limestone, carbonate rock, salt beds, or rocks that can naturally be dissolved by groundwater circulating through them. As the rock dissolves, spaces and caverns develop underground. Sinkholes are dramatic because the land usually stays intact for a while until the underground spaces just get too big. If there is not enough support for the land above the spaces, then a sudden collapse of the land surface can occur.
A sinkhole is an area of ground that has no natural external surface drainage–when it rains, the water stays inside the sinkhole and typically drains into the subsurface. Sinkholes can vary from a few feet to hundreds of acres and from less than 1 to more than 100 feet deep. Some are shaped like shallow bowls or saucers whereas others have vertical walls; some hold water and form natural ponds.
Typically, sinkholes form so slowly that little change is noticeable, but they can form suddenly when a collapse occurs. Such a collapse can have a dramatic effect if it occurs in an urban setting.
Common Causes
Sinkholes can be caused by a variety of natural and human-related factors. One of the most common natural causes is the erosion of underground rock by rainwater or groundwater, which slowly dissolves soft materials like limestone. Prolonged or intense rainfall and flooding can accelerate this process, increasing the likelihood of a collapse. Human activities such as construction, drilling, and the excessive pumping of groundwater can also weaken the ground, making it more prone to sinking and forming sinkholes.
Sinkhole Videos
Ever wondered how sinkholes form? Are you concerned there may be a sinkhole on your property? We sat down with Ty Black, a local karst geology and sinkholes expert to answer these questions and more about sinkholes that form in Michigan.