Cupola Pond

Points of Interest:

• See a fantastic sinkhole pond that is a National Natural Landmark.
• Look at water tupelo trees growing far removed from their typical southeastern lowlands range.
• On damp and warm spring days and evenings listen to the primordial sounds of hundreds of toads and frogs calling across the sinkhole pond swamp.

Natural History:

Cupola Pond is a swamp located in a sinkhole, a depression caused by a dissolving of the underlying rock, in this case dolomite, followed by a collapse of the land’s surface. The sinkhole basin is around 40 feet lower than the surrounding ridge. Here a five acre depression holds water and supports plants and animals not typical of the surrounding dry Ozark woods. Unlike most sinkholes, Cupola Pond has clay lenses and peat deposits that prevent water from quickly entering cave conduits below. This allows water to pond during all but drought years.

Cupola Pond is a mysterious place where century old water tupelos form a canopy over a shallow wetland with scattered patches of buttonbush, sedges, and mosses. Water tupelo is typically found growing in the Mississippi Lowlands region with bald cypress. Also unusual is the rare epiphytic sedge that grows on old logs and hummocks that stick out of the pond’s water. This sedge is typically found growing in the coastal plain swamps of the southeast. Fishless ponds such as this are very important breeding habitat for amphibians. At least seven amphibian species use the area including the rare wood frog, the marbled salamander, and the spotted salamander. In the spring the chorus of frogs and toads can be deafening.

Researchers have probed the depths of the sediments below Cupola Pond and have cored down nearly 40 feet. They have found sediments below the pond dating back 23,000 years. The sediments of the pond have been gathering pollen grains from surrounding vegetation for thousands of years. This has allowed researchers to determine the types of vegetation growing around Cupola Pond for the past 20,000 years. 18,000 years ago the area around the pond was dominated by spruce and fir trees. This occurred when much of the upper midwest was covered by glaciers. At around 12,000 years ago the trees growing around the pond included ash, oak, hickory, and hornbeam. 7,000 years ago the climate of Missouri warmed and dried and prairies expanded across the state. Pollen records from Cupola Pond for that time indicate oak, hickory, and grasses, sedges, and composites dominated the surrounding hills. Only in the last few thousand years have shortleaf pines become established in the uplands and tupelo gum became dominant in the pond itself.