A topographic depression (unless filled) in which bedrock is dissolved
or collapsed. Sinkholes may be open, covered, buried, or partially filled
with soil, field stones, vegetation, weathered bedrock, water, or other miscellaneous
debris. Sinkholes are usually circular, funnel-shaped, or elongated. Sinkhole
dimensions vary by region. Wisconsin sinkholes generally range between 20
to 30 feet in diameter and 4 to 10 feet deep, although some can be wider
and/or deeper. The sinkhole pictured here is in Vernon County, Wisconsin.
Solution enlarged or widened bedrock fracture that usually narrows with depth. The enlarged fracture,
also called a joint, shown here is from Brown County.
linear feature, including stream segment, vegetative trend, and
soil tonal alignment. This bedrock fracture, or vegetation lineament,
is near Bayshore Park, Brown County.
A natural cavity, large enough to be entered, that is connected to
subsurface passages in
bedrock. Pictured top row left is the entrance
to a cave in Door County; top row right,
a sinkhole that leads to a cave in Monroe County. bottom
row, two views
of the entrance to Wequiock Cave in Brown County, Wisconsin.
A place where surface or stormwater drainage disappears underground.
The swallet shown here is in Brown County.
A man-made shaft, tunnel, cave, hole, or other feature created for mining purposes.
This mine feature is a shaft entrance rock pile in Iowa County.
Extensive bare areas of exposed bedrock surfaces with many enlarged fractures
or sinkhole features.
Intermittent or permanent seepage of water from ground surface or bedrock outcrop
or karst area.
Closed depression in a karst area containing standing water.
Marsh formed by plants overgrowing a karst lake or seepage area.
to Sinkholes page.