Crystal Cave (Wisconsin)
‘’’Crystal Cave’’’ is a cave located in Wisconsin’s Pierce County, Near the Town of Spring Valley on Highway 29. The cave discovered in 1881 by local brothers George and William Vanasse. Crystal Cave is a Multi-level Soluntional cave formed in Dolomite bedrock in the Prairie Du Chien group. The Dolomite was formed 485 million years ago during the Lower Ordovician Period when a warm shallow ocean covered much of Minnesota and Wisconsin. The cave also holds the distinction of being Wisconsin’s longest known cave.
As mentioned above, Crystal Cave is a Solutional cave, of Multi-level Maze Type (consisting of 3 levels total). It extends to a depth of 69 ft. (21 m.) and is 4600 ft. (1.4 km.) in length, contained completely in the Prairie Du Chen group. The Bedrock forming the cave walls formed during the Ordovician Period of Earth’s History. The third level is the most extensive of the three having developed along existing Northeast to Southwest trending joints in the bedrock. Dating the period that the cave began to form has proven difficult due to erosion by Glacial waters, and the deposit of debris during the Wisconsin Glaciation, from the nearby Terminus of the Laurentide Ice Sheet’s Superior Lobe. the commonly accepted theory of the cave's formation is that The cave was formed by a weak carbonic acid solution formed from rainwater/snowmelt that mixed with biogenic carbon dioxide found in the topsoil, which then infiltrated existing joints and fractures in the bed rock expanding them into the openings that make up the cave’s passageways. Some have advanced that the cave's formation is actually hypogenic in origin.
The cave is host to a wide variety of cave formations, mostly concentrated in the Southeast portions of the cave where conditions are optimal for their growth. The Speleothems present in the cave take a number of forms most commonly: stalactites (including the variant known as soda straws), stalagmites, columns, flow stone, draperies, and ribbons, but also including: helectites, and cave pearls in rarer instances.
The cave was discovered in 1881 by a local youth named William R. Vanasse who discovered the entrance to the cave when he was exploring a leaf-filled sink in a farm field near his home. Initial exploration of the cave was performed by William along with his younger brother George. The brothers repelled into the cave using rope via the “original entrance” located now near the gift shop.
The cave, and the property was developed into it a show cave by local advertiser, and amateur Geologist Henry A. Friede of Eau Claire, WI. Fiede had been interested in opening a show cave for some time, having been inspired by the success of similar Business ventures, such as Blue Mounds (modernly known as Cave of the Mounds), and the show caves near the City of Harmony, Minnesota. The mostly likely prospect was finally decided to be what was at the time known as “Sander’s Corner Cave”.
The land was purchased by Friede and shortly after on 2 November 1941 work was started to remove the glacial debris left in the cave, that filled many of the passages on the 2nd and 3rd levels of the cave. At this same time, a local architect by the name of Alvin Peterson was engaged by Henry to design the future Entrance Building.
By April 1942 much of the debris had been removed and construction was begun on the entry building that had been designed by Peterson. The newly christened “Crystal Cave” was set to open on the Memorial Day weekend of 1942, but this plan was disrupted by heavy rains in the area, estimates claim that about 15–20 cm (6-8 inches) fell over the course of about 30 hours on Friday May 29, to Saturday May 30, causing massive flooding in the Spring Valley area (~2 meters [6–7 ft.] of flood water was recorded). Due to this, the opening of the cave delayed until 7 June 1942.
The period following the 1942 opening of the cave to the public saw little exploration beyond the 400 m (1300 ft.) that was excavated to open the original tour route. This was due to known side leads in the cave being considered too narrow for exploration by the Friedes, and following owners. This remained the case until 1986, when the cave was acquired by Geologists Blaze and Jean Cunningham. The Cunninghams opened the cave (and surrounding property) to exploration by both the Minnesota Speleological Survey, and the Wisconsin Speleological Society, leading to the discovery of several passages within Crystal Cave. These new passages are considered “wild cave” meaning that no commercial development of them is planned. This policy has been continued when the cave came under new ownership in 2012; the cave was purchased by Eric, and Kristen McMaster.
Since the opening of the property to cave explorers, a number of other caves has been discovered. These caves are not generally open to the public, only being accessed during private events. The only exception to this is South Portal cave, which was opened to the public via "Wild Tours" in August 2015.
In September 2014, a Weather Monitoring station was installed on the property. The station is through the Citizen Weather Observer Program to provide more accuracy in weather predictions for the surrounding area 
in late June 1942, the cave was designated as a public bomb shelter when Henry Friede, made offer of the cave for such a purpose to the Village Board of Spring Valley, WI. At the time, the cave held the distinction of being the only shelter in the Midwestern United States of America able to hold the entire population of the town it was intended to protect 
- Jean Cunningham; Holly A. S. Dolliver; William S. Cordua (2011). "Flaming meteors, dark caves, and raging waters—Geological curiosities of western Wisconsin". Field Guides. 24: 411–424.
- Spring Valley Sun, "Crystal Cave, Spring Valley, Open With Program on Memorial Day" Vol. XLIX No.22
- Spring Valley Sun, "Crystal Cave Postponed Opening Set For Next Sunday" June 4, 1942
- Bird, Kaye (2012). “It’s been a good ride (part 2): Crystal Cave has new owners” Gateway News
- Sarah Young "Crystal Cave adds new "wild" tour" Pierce County Herald, August 5, 2015, Page 3A
- Bird, Kaye (2014). “Local weather station up and running” Gateway News
- Spring Valley Sun, "Cave Now Official Valley Bomb Shelter" June 25, 1942
|Wikimedia Commons has media related to Crystal Cave (Wisconsin).|