The Yonaguni Monument is a massive underwater rock formation

Rock formation

This is a list of rock formations that include isolated, scenic, or spectacular surface rock outcrops. These formations are usually the result of weathering and erosion sculpting the existing rock...

 off the coast of Yonaguni

Yonaguni

is one of the Yaeyama Islands. It is the westernmost inhabited island of Japan and lies from the east coast of Taiwan, between the East China Sea and the Pacific Ocean proper....

, the southernmost of the Ryukyu Islands

Ryukyu Islands

The , also known as the , is a chain of islands in the western Pacific, on the eastern limit of the East China Sea and to the southwest of the island of Kyushu in Japan. From about 1829 until the mid 20th century, they were alternately called Luchu, Loochoo, or Lewchew, akin to the Mandarin...

, in Japan

Japan

Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

. There is a debate about whether the site is completely natural, is a natural site that has been modified, or is a manmade artifact.

The site is variably referred to as the and the in Japanese.

Discovery

The sea off Yonaguni is a popular diving location during the winter months due to its large population of hammerhead shark

Hammerhead shark

The hammerhead sharks are a group of sharks in the family Sphyrnidae, so named for the unusual and distinctive structure of their heads, which are flattened and laterally extended into a "hammer" shape called a "cephalofoil". Most hammerhead species are placed in the genus Sphyrna while the...

s. In 1987, while looking for a good place to observe the sharks, Kihachiro Aratake, a director of the Yonaguni-Cho Tourism Association, noticed some singular seabed formations resembling architectonic

Architectonic

Architectonic may mean:*pertaining to architecture, or suggesting the qualities of architecture*in Aristotelianism, as well as Kantianism, systematization of all knowledge...

 structures. Shortly thereafter, a group of scientists directed by Masaaki Kimura

Masaaki Kimura

Masaaki Kimura is a Professor Emeritus from the Faculty of Science of the University of the Ryukyus, Okinawa, Japan...

 of the University of the Ryūkyūs

University of the Ryukyus

The , abbreviated to Ryūdai , is a national university of Japan. It is located in the town of Nishihara on Okinawa Honto in Okinawa Prefecture. There are also campuses in Nakagusuku and Ginowan. It is the westernmost national university of Japan and the largest public university in Okinawa Prefecture...

 visited the formations. Kimura is a strong advocate of the view that the formations are artificial (manmade).

The formation has since become a relatively popular attraction for divers, in spite of the strong currents. In 1997, Japanese industrialist Yasuo Watanabe sponsored an informal expedition comprising writers John Anthony West and Graham Hancock

Graham Hancock

Graham Hancock is a British writer and journalist. Hancock specialises in unconventional theories involving ancient civilizations, stone monuments or megaliths, altered states of consciousness, ancient myths and astronomical/astrological data from the past...

, photographer Santha Faiia, geologist Robert Schoch, a few sport divers and instructors, and a shooting crew for British Channel 4 and Discovery Channel

Discovery Channel

Discovery Channel is an American satellite and cable specialty channel , founded by John Hendricks and distributed by Discovery Communications. It is a publicly traded company run by CEO David Zaslav...

. Another notable visitor was freediver Jacques Mayol

Jacques Mayol

Jacques Mayol was the holder of many world records in free diving.Jacques Mayol was a French national born in Shanghai, China. He was the first free diver to descend to 100 meters , and he managed to descend to 105 meters when he was 56 years old...

, who wrote a book on his dives at Yonaguni. A plaque in his honor was fixed to the undersea formations after his suicide in 2001.

Main features

The Monument consists of medium to very fine sandstone

Sandstone

Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...

s and mudstone

Mudstone

Mudstone is a fine grained sedimentary rock whose original constituents were clays or muds. Grain size is up to 0.0625 mm with individual grains too small to be distinguished without a microscope. With increased pressure over time the platey clay minerals may become aligned, with the...

s of the Lower Miocene Yaeyama Group, deposited about 20 million years ago. Most of the significant formations are connected to the underlying rock mass (as opposed to being assembled out of freestanding rocks).
The main feature (the "Monument" proper) is a rectangular formation measuring about 150 by, and about 27 metre tall; the top is about 5 m (16.4 ft) below sea level. Most of its top surface consists of a complex series of terraces and broad steps, mostly rectangular, bounded by near vertical walls.

Some of its peculiar details include:

• Two closely spaced pillars which rise to within eight feet of the surface;
• The "Loop Road", a 5 m (16.4 ft) wide ledge that encircles the base of the formation on three sides;
• The "Totem", a stone column about 7 m (23 ft) tall;
• The "Dividing Wall", a straight wall 10 m (32.8 ft) long;
• The "Gosintai", an isolated boulder resting on a low platform;
• The "Turtle", a low star-shaped platform;
• The "Triangle Pool", a triangular depression with two large holes at its edge;
• The "Stage", an L-shaped rock.

Artificial structures

The flat parallel faces, sharp edges, and mostly right angles of the formation have led many people, including many of the underwater photographers and divers that have visited the site and some scholars, to the opinion that those features are man-made. These people include Gary and Cecilia Hagland and Tom Holden who went on underwater expeditions to study and photograph the site as well as Dr. Sean Kingsley, a marine archaeologist. These features include a trench that has two internal 90° angles as well as the twin megalith

Megalith

A megalith is a large stone that has been used to construct a structure or monument, either alone or together with other stones. Megalithic describes structures made of such large stones, utilizing an interlocking system without the use of mortar or cement.The word 'megalith' comes from the Ancient...

s that appear to have been placed there. These megaliths have straight edges and square corners. However sea currents have been known to move large rocks on a regular basis. Some of those who see the formations as being largely natural claim that they may have been modified by human hands. The semi-regular terraces of the Monument have been compared to other examples of megalithic architecture, such as the rock-hewn terraces seen at Sacsayhuaman

Sacsayhuamán

-External links:* BBC Article...

. The formations have also been compared to the Okinawa Tomb, a rock-hewn structure of uncertain age.

Other evidence presented by those who favor an artificial origin include the two round holes (about 2 feet wide, according to photographs) on the edge of the Triangle Pool feature, and a straight row of smaller holes which have been interpreted as an abandoned attempt to split off a section of the rock by means of wedges, as in ancient quarries

Quarry

A quarry is a type of open-pit mine from which rock or minerals are extracted. Quarries are generally used for extracting building materials, such as dimension stone, construction aggregate, riprap, sand, and gravel. They are often collocated with concrete and asphalt plants due to the requirement...

. Kimura believes that he has identified traces of drawings of animals and people engraved on the rocks, including a horse-like sign that he believes resembles a character from the Kaida script. Some have also interpreted a formation on the side of one of the monuments as a crude moai

Moai

Moai , or mo‘ai, are monolithic human figures carved from rock on the Chilean Polynesian island of Easter Island between the years 1250 and 1500. Nearly half are still at Rano Raraku, the main moai quarry, but hundreds were transported from there and set on stone platforms called ahu around the...

-like "face".

Supporters of artificial origin also argue that, while many of the features seen at Yonaguni are also seen in natural sandstone formations throughout the world, the concentration of so many peculiar formations in such a small area is highly unlikely. They also point to the relative absence of loose blocks on the flat areas of the formation, which would be expected if they were formed solely by natural erosion and fracturing.

If any part of the Monument was deliberately constructed or modified, that must have happened during the last Ice Age

Ice age

An ice age or, more precisely, glacial age, is a generic geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers...

, when the sea level was much lower than it is today (e.g. 39 metre lower around 10,000 years BCE). During the Ice Age, the East China Sea

East China Sea

The East China Sea is a marginal sea east of China. It is a part of the Pacific Ocean and covers an area of 1,249,000 km² or 750,000 square miles.-Geography:...

 was a narrow bay opening to the ocean at today's Tokara Gap. The Sea of Japan

Sea of Japan

The Sea of Japan is a marginal sea of the western Pacific Ocean, between the Asian mainland, the Japanese archipelago and Sakhalin. It is bordered by Japan, North Korea, Russia and South Korea. Like the Mediterranean Sea, it has almost no tides due to its nearly complete enclosure from the Pacific...

 was an inland sea and there was no Yellow Sea

Yellow Sea

The Yellow Sea is the name given to the northern part of the East China Sea, which is a marginal sea of the Pacific Ocean. It is located between mainland China and the Korean Peninsula. Its name comes from the sand particles from Gobi Desert sand storms that turn the surface of the water golden...

; people and animals could walk into the Ryukyu peninsula from the continent. Therefore, Yonaguni was the southern end of a land bridge

Land bridge

A land bridge, in biogeography, is an isthmus or wider land connection between otherwise separate areas, over which animals and plants are able to cross and colonise new lands...

 that connected it to Taiwan

Taiwan

Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...

, Ryūkyū, Japan and Asia

Asia

Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

. This fact is underscored by a rock pillar in a now-submerged cave that has been interpreted as a fused stalactite

Stalactite

A stalactite , "to drip", and meaning "that which drips") is a type of speleothem that hangs from the ceiling of limestone caves. It is a type of dripstone...

-stalagmite

Stalagmite

A stalagmite is a type of speleothem that rises from the floor of a limestone cave due to the dripping of mineralized solutions and the deposition of calcium carbonate. This stalagmite formation occurs only under certain pH conditions within the underground cavern. The corresponding formation on...

 pair, which could only form above water.

Kimura first estimated that this must be at least 10,000 years old (8,000 BCE) dating it to a time when it would have been above water. In a report given to the 21st Pacific Science Congress in 2007 he revised this estimate and dated it to 2,000 to 3,000 years ago as the sea level then was close to current levels.

The existence of an ancient stoneworking tradition at Yonaguni and other Ryukyu islands is demonstrated by some old tombs and several stone vessels of uncertain age.

Natural formation

Some of those who have studied the formation, such as geologist Robert Schoch of Boston University, state that it is most likely a natural formation, possibly used and modified by humans in the past. Schoch observes that the sandstones that make up the Yonaguni formation "contain numerous well-defined, parallel bedding planes along which the layers easily separate. The rocks of this group are also criss-crossed by numerous sets of parallel and vertical (relative to the horizontal bedding planes of the rocks) joints and fractures. Yonaguni lies in an earthquake-prone region; such earthquakes tend to fracture the rocks in a regular manner." He also observes that on the northeast coast of Yonaguni there are regular formations similar to those seen at the Monument. Schoch also believes that the "drawings" identified by Kimura are natural scratches on the rocks. This is also the view of John Anthony West.

Patrick D. Nunn, Professor of Oceanic Geoscience at the University of the South Pacific

University of the South Pacific

The University of the South Pacific is a public university with a number of locations spread throughout a dozen countries in Oceania. It is an international centre for teaching and research on Pacific culture and environment. USP's academic programmes are recognised worldwide, attracting students...

, has studied these structures extensively and notes that the structures below the water continue in the Sanninudai slate cliffs above, which have "been fashioned solely by natural processes" and concludes in regard to the underwater structures that "there seems no reason to suppose that they are artificial."

Other examples of natural formations with flat faces and sharp straight edges are the basalt columns of the Giant's Causeway

Giant's Causeway

The Giant's Causeway is an area of about 40,000 interlocking basalt columns, the result of an ancient volcanic eruption. It is located in County Antrim on the northeast coast of Northern Ireland, about three miles northeast of the town of Bushmills...

 and the natural staircase formation on Old Rag Mountain

Old Rag Mountain

Old Rag Mountain is a popular hiking destination with a summit elevation of , located in the Blue Ridge Mountains of the Shenandoah National Park in Virginia's Madison County, near Sperryville....

.

Media references

James Rollins

James Rollins

* For the American baseball pitcher, see Jim Czajkowski* For the American baseball shortstop, see Jimmy Rollins* For the 19th century American politician from Missouri, see James S. Rollins...

' book Deep Fathom, while not explicitly mentioning the Monument, features scenes "off the coast of Yonaguni Island" involving man-made pyramid

Pyramid

A pyramid is a structure whose outer surfaces are triangular and converge at a single point. The base of a pyramid can be trilateral, quadrilateral, or any polygon shape, meaning that a pyramid has at least three triangular surfaces...

-like structures known as The Dragons that emerged above the surface after widespread seismic activity.

The Yonaguni Monument is important in Graham Hancock's documentary Quest for the Lost Civilization.

The monument was featured on episodes of Ancient Aliens

Ancient Aliens

Ancient Aliens is an American television series that premiered on April 20, 2010 on the History channel. Produced by Prometheus Entertainment, the program presents theories of ancient astronauts and proposes that historical texts, archaeology and legends contain evidence of past...

and History's Mysteries

History's Mysteries

History's Mysteries is an American documentary television series on the History Channel.-Overview:The 154 episodes of the series were produced from 1994-2006. Each season consisted of 12 to 14 one-hour episodes that focused on historical events or subjects considered to be mysterious by the general...

both on The History Channel

The History Channel

History, formerly known as The History Channel, is an American-based international satellite and cable TV channel that broadcasts a variety of reality shows and documentary programs including those of fictional and non-fictional historical content, together with speculation about the future.-...

.

See also

• Atlantis
  Atlantis
  Atlantis is a legendary island first mentioned in Plato's dialogues Timaeus and Critias, written about 360 BC....
  
  
• Bimini Road
  Bimini Road
  The Bimini Road, sometimes called the Bimini Wall, is an underwater rock formation near North Bimini island in the Bahamas. The Road consists of a -long northeast-southwest linear feature composed of roughly rectangular to subrectangular limestone blocks....
  
  
• Dvaraka (historical)
• Marine archaeology in the Gulf of Cambay
• UNESCO Convention on the Protection of the Underwater Cultural Heritage
  UNESCO Convention on the Protection of the Underwater Cultural Heritage
  The UNESCO Convention on the Protection of the Underwater Cultural Heritage, adopted by the UNESCO General Conference on 2 November 2001 is an international treaty aimed at saving the underwater cultural heritage....