Jordbrugrotta

src: images.cdn.yle.fi

Jordbrugrotta (also known as Pluragrotta) is a cave in Rana, Norway. It is the deepest cave in Northern Europe.

Jordbrugrotta is the most dived cave in Scandinavia, making it a popular cave diving destination. The majority of the other ~200 caves in Rana are not suitable for diving, and formation of new caves is limited due to granite formations in the ground. The damming of Kallvatnet made diving in Jordbrugrotta possible. There have been multiple cases of fatalities and injuries among visiting cave divers.

The cave's passages were formed by the river Plura's flow on porous limestone. Rock formations include marble. Visibility in the cave is high.

Video Jordbrugrotta

Discovery and exploration

Jordbrugrotta was discovered in 1966 by an English team of cave explorers.

Damming of lake Kallvatnet in the mid 1960s decreased the flow of the river Plura enough to allow diving in the cave. The river still flows partially underground.

Norwegian divers have explored the passages since the 1990s. There has been a rivalry between Finnish and Norwegian divers about exploration of the cave system. Two Norwegian divers' organizations have been exploring the cave system. Norsk Teknisk Dykkekrets did much of early surveying, and since 2002 Reel Action Diving has continued the work. Finnish explorers discovered connection between two entrances of the cave first in September 2013. The cave has attracted Finns in recent years.

Exploration is complicated by cold water and narrow passages in the underwater cave system. Side passages make it possible to get lost in the cave. Connection between Plura and Steinugleflåget caves was not discovered for dozens of years, and the discovery was complicated by the dry cave Steinugleflåget's difficult position. Reaching its head pool requires vertical climbing of over 100 meters. On the other hand, visibility in the cave's water is considered to be extremely good. It is possible to see up to 20 meters horizontally. In addition of the usually good visibility, the cave is open on all seasons.

Maps Jordbrugrotta

Geology

The cave's passages were formed by river Plura's flow on porous limestone. Rock formations include marble. Most of the other approximately 200 caves in Rana are not suitable for diving, and formation of caves has been limited due to granite forming most of the ground. Another similar diveable cave nearby is Litjåga. The caves are beneath Scandinavian Mountains.

Sediments, boulders and sands in the cave appear to be from a periglacial or subglacial origin.

src: www.speleo.no

Fauna

Harsh climate in Norway limits the amount of species living in caves in comparison to Southern Europe. However, several different invertebrates have been identified by a study to live in Jordbruggrotta. It is believed that there are no fish living in the cave (but footage in the 2016 documentary Diving into the Unknown clearly shows a fish in one scene).

Species living in the cave include:

• Arpedium quadrum
• Belba sp.
• Chamobates cuspidatus
• Desoria olivacea
• Dicyrtoma fusca
• Leptus sp.
• Liogluta alpestris
• Oxypoda spectabilis
• Porrhomma convexum
• Psephidonus longipes
• Siphonoperla burmeisteri

src: images.cdn.yle.fi

Diving accidents

Compared to amount of cave divers, accidents have been relatively uncommon at Jordbrugrotta.

One of the divers who was exploring the cave in August 1988 had a hole torn in his diving suit's right leg by a sharp rock. He survived the incident with a mild case of hypothermia.

On 16 August 2006, a Norwegian diver was reported missing. His body was recovered on 28 August 2006 by a team of British divers.

On 6 February 2014 two Finnish divers died at the cave, and three other divers were injured. Survivors suffered from decompression sickness. Norwegian authorities summoned an international team including British divers Richard Stanton, John Volanthen and Jason Mallinson to recover the bodies. After diving to the site, they deemed the operation too difficult. A diving ban was later given for the cave. However, the involved Finnish divers returned later without official authorisation and recovered the bodies. Their recovery expedition was filmed as the documentary Diving Into The Unknown. The diving ban was overturned on 31 March 2014.

src: httpsak-a.akamaihd.net

See also

• Tjoarvekrajgge - the longest cave in Scandinavia

src: httpsak-a.akamaihd.net

References

src: rana.speleo.no

Further media

• Juan Reina (2016). Takaisin pintaan [Diving into the Unknown] (in Finnish). Monami Agency Oy. 
• Taija Nevalainen. "Plura Cave Deep Exploration 2012, depth 132m". 
• William Kremer. "The cave divers who went back for their friends". 
• "Sukellusryhmä: Ruumiiden nosto kuvattiin, 110 tuntia sukellusta". MTV3 (in Finnish and English). 28 March 2014. 
• Lars Christian Wegner. "VG takes you through dramatic diving death in the Plura cave and the following rescue operation". 
• Petri Raivio; Paula Tapiola. "Suomalaiset sukeltajat hakivat kuolleet kaverinsa ylös Norjassa". 
• Fauna Norvegica. Norsk Zoologisk Tidsskriftsentral. 1984. 
• D. Tarling; F. Hrouda (31 May 1993). Magnetic Anisotropy of Rocks. Springer Science & Business Media. p. 103. ISBN 978-0-412-49880-0. 
• Monica Bring Estensen; Fredrik Svendsen. "Omkomne dykkere hentet opp fra Pluragrotta". 

src: g.acdn.no

External links

• Norsk Grottedykkerforbund
• Plura line-map
• Diving in Steinuglefloget

Source of article : Wikipedia