Cave of the Mounds

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Inside Cave of the Mounds

The Cave of the Mounds is a natural limestone cave located in Blue Mounds, Wisconsin, USA, and is named for two nearby hills called the Blue Mounds. More specifically, it is located in the southern slope of the east hill. The cave's beauty comes from its many varieties of mineral formations called speleothems, because of this it is often called the “jewel box” of the major American caves.^[1] The Chicago Academy of Sciences considers the Cave of the Mounds to be "the significant cave of the upper Midwest" because of its beauty.^[1] In 1988, the United States Department of the Interior and the National Park Service designated the cave as a National Natural Landmark.^[2]

1 History
2 Formations
3 Tourism
4 Footnotes
5 References
6 External links

[edit] History

The limestone that the cave is carved from began to form approximately 488 million years ago, during the Ordovician Period of Earth's geologic history ^[2]. During this period, much of North America was covered with warm, shallow seas where many shellfish thrived. Over millions of years, the shells left behind by these shellfish accumulated to form enormous quantities of limestone. The particular type of limestone that the cave was formed in is called galena dolomite because of its high concentration of the lead ore galena.

The cave began its formation about a million to a million and a half years ago.^[3] The actual formation of the Cave of the Mounds is similar to many caves. A large crack in the surface of the rock, called the cave's "lifeline", allows rain water to seep into the stone. In the air, rain combines with carbon dioxide to form a weak carbonic acid. This acid is not very strong, but it is strong enough to dissolve away the limestone after it seeps in through the "lifeline". Over time, large cavities were dissolved in the stone and as the water table dropped, the water drained out and the cavities were filled with air. Now that the cavities are filled with air instead of water, the water droplets coming from the "lifeline", which are saturated with dissolved calcium carbonate, are able to deposit solid calcium carbonate. The deposited minerals over time build up to create various speleothems. This is a very gradual process, usually taking 50 to 150 years to form one cubic inch of material,^[3] and continues to this day.

The area around the Blue Mounds, Dane County, was first settled in 1828 by Ebenezer Brigham, a successful lead miner from Massachusetts. He traveled to Wisconsin in order to join in the lead rush during the late 1820s. After arriving, he set up his operations just north of where the cave lies today. Ebenezer's house later became a trading post, an inn, a stagecoach stop, and the first post office in Dane County. Ebenezer Brigham later became Colonel Brigham and helped build and command Fort Blue Mounds during the Blackhawk War. He died after a long life, not knowing that a beautiful cave existed underneath his Brigham Farm.

On August 4, 1939, Cave of the Mounds was accidentally discovered when limestone quarry workers blasted a section of the quarry and exposed an opening to the cave.^[2] Work at the quarry then immediately stopped and was never continued. Soon afterwards, the cave was closed to prevent damage from curious cave seekers who came to remove pieces of stalactites and stalagmites to take home as souvenirs. The cave was reopened later in May, 1940, after lights and wooden walkways were installed. Since then, the wooden walkways have been replaced with concrete ones in order to accommodate the many visitors. Theatrical lighting has also been installed to further exemplify the colors and shapes inside the cave. Later in 1988, the cave was designated a National Natural Landmark by the United States Department of the Interior and the National Park Service. To be considered a NNL, "a site must be one of the best examples of a natural region's characteristic biotic or geologic features."^[4]

[edit] Formations

The Cave of the Mounds is home to many different varieties of speleothems. As with most caves, stalactites and stalagmites are common. Formations found inside the cave include:

Soda straws - Soda straws are a type of formation that is characterized by a thin, hollow tube made of minerals. They have the potential to form into stalactites if the hole at the bottom of them gets plugged.
Flowstones - Flowstones are created when water travels along a surface and deposits minerals. In limestone caves, flowstones are generally the most common type of formation.
Curtains - These are formed when water droplets run along the ceiling of the cave and gradually form sheets of minerals.
Lily pads - Lily pads are created when water droplets fall into a puddle and create a formation on the surface reminiscent of a lily pad.
Helictites - Helictites are an unusual form of stalactite that grow with bends or angles in them seeming defying gravity. Their strange growth style is most likely caused by capillary forces acting on the water droplets.
Oolites - Also called "cave pearls", they are a beautiful but rare speleothem found in this cave. These are spherical formations made when a droplet falls onto some sand and calcite forms around the sand much like a pearl.

These formations come in many different brilliant colors such as reds, browns, blues, and grays. The reds and browns are caused by the presence of iron oxide in the formation. Similarly, blues and grays are caused by manganese oxide. Some speleothems are even partially luminescent and give off light for a brief period after exposure to another light. Somewhere in the cave, there is a large orthoceras that you can spot

[edit] Tourism

The cave is located 20 miles west of Madison, off of the U.S. Highways 18/151 in Blue Mounds, WI. It is about a two hour drive from Milwaukee. Since its opening in 1940, the cave has hosted millions of tourists.^[3] Other nearby attractions include:

The House on the Rock - a "house" atop a 60ft tall chimney of rock^[5]
Mount Horeb - home to many life-size troll carvings made from tree stumps, found along the main street which is now referred to as "The Trollway"
Little Norway - a valley located in the foothills of Blue Mounds, WI
Mustard Museum - the world's largest collection of prepared mustards
Tyrol Basin - a ski and snowboard hill
Botham Vineyards
Circus World - museum with more than 200 circus wagons as well as thousands of posters, photos, and films.
Taliesin (studio) - Frank Lloyd Wright's home where he lived and worked for the majority of his career, later converted into the home of the Taliesin Fellowship