User:Speleo507/sandbox/Niagara Cave, Harmony MN

Niagara Cave is a commercial cave located southwest of Harmony, Minnesota, USA. It features an underground waterfall and has been rated as one of the best commercial caves in the United States listed among such internationally renowned marvels as Jewel Cave National Monument in South Dakota, Carlsbad Caverns National Park in New Mexico, Caverns of Sonora in Texas, Luray Caverns in Virginia, and Mammoth Cave National Park in Kentucky. Niagara Cave has a variety of speleothems including stalactites, stalagmites, flowstone. Fossils are another feature that can be observed embedded in the walls and ceilings of Niagara Cave. There are several species of long extinct life forms such as trilobites, gastropods, receptaculites, and shelled cephalopods.

History
In 1924 farmer Phil Todd, the operator of the farmland owned by John Kennedy (no known relation to President John F. Kennedy) discovered three of his pigs had escaped the barnyard. When after a short search didn’t produce any pigs, Mr. Todd asked Clifford Booth his hired hand, to get the assistance of Mr. Todd’s nephews, Howard and Gordon Elliot, who lived in the neighborhood and try to locate his missing livestock. It wasn’t long before the young men’s search led them to a large sinkhole]] located east of the homestead. When they determined the pigs had somehow managed to fall through a narrow crack at the bottom of the sinkhole, they got some ropes and lights and made their way down into the hole. After descending over fifty feet they found the pigs still alive on a rock ledge. But the living pigs were not their only discovery. They could see that the vast rooms and passageways extended far beyond what their dim lights could pierce. Nearly eight years later three cave explorers from the Decorah Iowa area got word of this interesting hole on the Kennedy farm. The three men; Joe Flynn, a newspaperman, promoter, and politician; Al Cremer, a road contractor; and Leo Tekippe, a ball player and boxer, had enjoyed exploring many small caves in the area. They decided to get permission from the Kennedy’s to determine if the rumors were true. After returning to the surface, the three men decided to develop the cave. They leased the land from John Kennedy and spent the next two years making the cave accessible. They leveled the walkways, installed staircases, bridges, and an elaborate electrical lighting system powered by a large diesel generator. They also built a replica of a miner’s shack over the entrance. The cave was officially opened to the public for tours June 1, 1934.

Geology
There are several requirements and conditions in order for a limestone cave to form.

Limestone
The cave is within limestone which was formed in a shallow epeiric sea 454–446 million years ago during the late Ordovician Period. Although the sinkhole entrance is within the very bottom of the Dubuqe limestone most of it cuts through the Galena Group. A plethora of life lived in this salt water sea many of which can be found as fossils within Niagara Cave. As the inland sea transgressed and regressed, different sedimentary deposits like limestone and shale were laid down intermittently on the sea floor. During the late Mesozoic Era the last of the inland seas retreated as evidenced by the paleontology in Minnesota.

Chemical Dissolution and Physical Erosion
Glacial activity has shaped much of Minnesota’s topography. Niagara Cave is within the Driftless Area of southeastern Minnesota where no glacial drift covered the region in the last glacial period. The Driftless Area is dominated by karst topography where the exposure of Ordovician limestone to slightly acidic water (carbonic acid) from rainwater and past glacial meltwater has allowed chemical dissolution and physical erosion underground. Collapsed sinkhole features sometimes lead into small caverns that were previously dissolved or eroded away. Niagara Cave is one such feature.

Other Geology
Speleothems grow in the dissolved cavities of limestone (calcium carbonate) as the result of a chemical reaction. Water (H2O) may combine with carbon dioxide (CO2) gas naturally found in the air or soil to form carbonic acid (H2CO3). This lowers the pH level of the solution. When the carbonic acid seeps into the limestone, it dissolves the calcium carbonate (mineral calcite CaCO3) to form calcium bicarbonate, or Ca(HCO3)2. After this solution enters a cavity, or cave, it degases. Degassing results when the carbon dioxide escapes the solution due to a change in pressure. The remaining water, with calcite suspended within it, drips from the ceiling or flows along the walls and precipitation of calcite occurs, forming stalactites or flowstone. The accumulation of calcite on the ground may form mounds called stalagmites.

The temperature inside the cave is a constant 48 °F, comparable to that of Forestville Mystery Cave State Park. The temperature is determined by the average air temperature of southeastern Minnesota.

Description
The entrance of Niagara Cave is through the gift shop building which now covers the sinkhole where the pigs fell through in 1924. There is a series of staircases with about 100 steps before reaching the main artery of the cave. This first Reception Room is about 80 ft below the surface and splits into two opposite directions. Taking the northeast route down several more flights of stairs leads to Niagara Cave's Wishing Well where a 6 ft deep pool of water accumulates before flowing south-southeast. Following above the water on a wooden-then cement- walkway a series of waterfalls begin until falling off the largest drop of about 50 ft. This waterfall is the namesake of Niagara Cave and is in the largest room so far discovered in this cave system, the Waterfall Dome Room. On a bridge overlooking the waterfall the depth is estimated to be 120 ft below the surface. Returning to the Reception Room the path continues in a southwest direction. There is a Wedding Chapel in Niagara Cave where there have been over 400 weddings performed since 1934. The cave is mostly linear, trending in the direction of limestone joints. Many speleothems grow along the walls of the cave such as flowstone, ribbon stalactites, and draperies. There is a chamber just beyond the Wedding Chapel where low voices can create a reverberating echo. The ceilings of the passageways beyond this echo chamber remain 20-30 ft high. The walls are curved and pockmarked.

About 650 ft into the cave the passages begin to narrow and the height of the ceiling increases. Although this middle portion of the cave is rather dry and leaves little allowance for speleothem growth, many fossils can be found in this narrower section of the cave. After a set of stairs the main artery of the cave extends for almost 400 ft in a straight stretch. This hallway called the Grand Canyon cuts through a layer of chert nodules near the end. The ceiling at the end of the Grand Canyon is estimated to be around 100 ft high. Down a narrow staircase leads to the Cathedral Dome Room. It is similar in appearance to the Waterfall Dome Room, however, this room is smaller and the perspective is from the floor instead of on a bridge. The last two easily accessible rooms have an abundance and diversity of stalactites and are aptly name the Stalactite Rooms. From the last platform of the cave, the stream (previously seen from the waterfall) can just be seen on the norther side of the room. Although this is the end of the commercial section of the cave, the cave does continue on both through the water channel and along the muddy floor.

The last room of the cave apart from where the stream continues is called the Star Room and is not accessible to the public. The stream from the Wishing Well, Waterfall, and Stalactite Rooms continues for About 1-2 mi into the before emptying into the Upper Iowa River through a small spring.