Harry's Wacky World

International Union of Speleology (UIS)

13th International Symposium on Vulcanospeleology
Jeju Island, Republic of Korea
September 1 through 10, 2008

All photos are Copyright 2008 by Harry M

INTRODUCTION

The UIS Commission on Volcanic Caves held its 13th International Symposium on Vulcanospeology on the island of Jeju in the Republic of Korea. This was my second vulcanospeleology symposium. I attended the 10th International Symposium on Vulcanospeology in Reykjavik, Iceland, in September 2000.

This was a very well-funded symposium thanks to the many sponsors: Jeju Island Cave Research Institute, Cave Research Institute of Korea, Korean Society of Cave Environmental Science, Cultural heritage Administration of Korea, Jeju Special Self-Governing Province, International Union of Speleology, Cheju National University, Hallim Park, Halla Ilbo and Hanil Tour.

The lava tube caves and volcanic land forms on Jeju Island are inscribed as a UNESCO World Natural Heritage Site.

Approximately forty people attended the symposium, representing the following nations:
Australia
Belgium
Bermuda
Brazil
Czech Republic
Germany
Hungary
Iceland
Israel
Italy
Japan
Korea
Lebanon
Netherlands
New Zealand
Norway
Portugal
Switzerland
United Kingdom
United States

JEJU ISLAND

Jeju Island is a shield volcano located off the southern tip of the Korean Penninsula. Jeju is the largest island in Korea, measuring 45 miles by 25 miles, and has almost 600,000 inhabitants. In the center of the island is a large shield volcano, Mount Halla, that is the highest peak in Korea at 6,400 feet. There are more than 300 other volcanic cones on Jeju Island.

Jeju Island is located off the southern tip of the Korean Penninsula in the Yellow Sea.

Jeju Island is known for its magnificent and unique lava tube caves. The caves on Jeju are some of the longest lava tubes in the world and contain spectacular lava formations. The caves on Jeju are also unique because they contain secondary calcium carbonate speleothems.

GEOLOGY

The geology of Jeju Island is well known because thousands of fresh water wells have been drilled all over Jeju Island. These core samples have given scientists a detailed view of the stratigraphy of the island.

In brief, Jeju Island consists of a granite basement overlain by marine sediments, all capped by volcanic rock. The basement rock of Jeju Island is granite of Jurrasic to Cretaceous age. Overlying the basement is an unconsolidated layer of quartoze sand and mud up to 2,500 feet thick. This layer (the U Formation) is thought to have accumulated during the Pliocene as continental shelf sediments. Then, beginning 1.8 million years ago, marine and non-marine volcanos begain erupting as the result of decompression melting. (A volcanic hotspot does not exist under Jeju.) The accumulating volcanic flows raised the island to its current height of 1,950 meters (6,400 feet).

THE SYMPOSIUM (SEP 1-5, 2008)

The symposium was held at the Sunshine Hotel in Hamdeok on the northeast coast of Jeju Island. Thirty-six speakers gave a variety of presentations regarding vulcanospeleology. Topics included the geology and caves of Jeju Island, cave and mineral science, new exploration in Argentina, Africa, Syria, Iceland and Chile, and the discovery of a Dodo bird skeleton in a lava cave in Mauritius.

The view from my hotel balcony.

Professor Woo Kyung Sik (Korea), host of the symposium.

A dinner banquet.

POST-SYMPOSIUM CAVING (SEP 6-10, 2008)

After the symposium, we went caving! The caves on Jeju are part of the UNESCO World Natural Hertitage Site. Thus all of the caves were gated and locked.

Handeul Cave

Haneul Cave is about 4,500 feet long, with two parallel passageways. There is a sizeable bat colony in the cave.

This is a great photo of the main passageway, clearly showing that the tube was a lava conduit.

Susan Cave

Susan Cave is a 14,800-foot lava tube, of which 4,000 feet is breakdown. Braiding passageway are present, as are lava falls and other common lava tube features. We were unable to reach the end of the cave in the time alloted because the unstable breakdown was very difficult to negotiate.

Inside of the entrance drop. This breakdown extended for 4,000 feet down the main passageway, making for very difficult travel.

Hayley (U.K.) with a turtle-like formation. We believe that this was a rafted block that became stuck and was subsequently modified by the passing lava flows.

Manjang Cave

Manjang Cave is one of the longest lava tubes in the world, with more than 24,000 feet of passageway. The passageways are also quite large, measuring up to 75 feet wide and 100 feet high. The cave has up to six known levels, a section of which has been developed into a commercial cave.

Manjang Cave is best known for it's fantastic lava formations. Included in these formations is the tallest known lava driblet column in the world, measuring over 25 feet in height.

The world's tallest lava driblet column (25 feet high). The ceiling collapsed, forming a rectangular hole. Lava flowing in a conduit above dripped down through the hole, forming this column. (There are only four known driblet columns in the world: Korea, Hawaii, New Mexico and Washington.)

Stephan (Germany) contemplates the processes that created this interesting flow formation. A rafted block diverted flow around itself. Flow direction is towards the camera.

Ed (U.K.) enjoying the Water pouring from ceiling cracks.

Black ropey pahoehoe lava.

Ed (U.K.) marvels at the pahoehoe floor detail.

Hyeon Im (Korea) stands behind a highly-oxidixed red lava that shows a secondary overflow pattern.

Stephan (Germany) rests on a collapsed ceiling in a formerly bi-level tube. Flow direction is away from the camera.

David (Australia) leads cavers through a lava tube with multiple well-developed flow lines on both walls. Notice the breakdown on the floor without obvious fragmanetation of the walls or ceilings. The breakdown may represent blocks that were rafted in the lava flow and carried into these positions by the flow.

Stephan (Germany) stops to admire a rare example of overflow onto a flow line. The flow line is actually a shelf that juts out from the wall, it's not a bench. Lava overflowed onto the flow line making these wonderful formations

Stein-Erik (Norway) examines a rare example of pillow-like lava in lava tube. Notice the two level tube in the background.

Yoncheondong Cave

Yoncheondong Cave is one of the most spectacular and unique lava tube caves in the world because of the calcium carbonate speleothems. Calcarious sand, blown inland from the beaches, overly many lava tubes on Jeju Island. Rain water that percolates through the lava dissolves the calcium carbonate and drips into the lava tubes. Stalagmites, stalactites, soda straws, flow stone, rim stone, cave flowers, cave pearls and variety of other speleothems form in the lava tubes just as they would in a limestone cave.

Yoncheondong Cave had no entrances, thus its senstive speleothems were protected. Then in 2005 electric company was drilling a to install a utility pole when they punched through into the cave. Currently the cave has two steel gates completely sealing the cave and an alarm system.

Yoncheondong Cave is approximately 8,200 feet long, 50 feet wide and 65 feet high. At the downstream end of the cave there is a fresh water sump that has been pushed by cave divers to within 100 meters of the sea.

We count ourselves as being extremely fortunate to have had the opportunity to visit this one-of-a-kind lava tube.

Calcarious sands are common on this volcanic island. These sands (and the wind and rain) are responsible for the fantastic speleothems.