"I think it should be considered a primarily natural structure until more evidence is found to the contrary. However, by no means do I feel that this is an absolutely closed case. The question of its genesis - - artificial versus natural - - may not be an all or nothing question. We should also consider the possibility that the Yonaguni Monument is fundamentally a natural structure that was utilized, enhanced, and modified by humans in ancient times. The Yonaguni Monument may even have been a quarry from which blocks were cut, utilizing natural bedding, joint, and fracture planes of the rock, and thence removed for the purpose of constructing other structures which are long since gone. On Yonaguni Island and elsewhere in the Okinawa area there appears to be an ancient tradition of modifying, enhancing, and improving on nature. On Yonaguni there are very old tombs (age unknown, but possibly on the order of thousands of years old) that stylistically appear to be comparable to the "architecture" of the Yonaguni Monument. There is still other evidence of some kind of human working of the local stone on Yonaguni. Scattered over the island are apparently very ancient (age unknown), obviously human-carved, stone "vessels." These are composed of local rock, and clearly were neither made nor transported to the island in modern (that is, in the last 500 years or so) times. These stone vessels remain somewhat of a mystery, as does the Yonaguni Monument and other underwater structures reported in the Okinawa area.
On Yonaguni beautifully crafted ancient stone tools have been found that could have been used to both shape some of the stone vessels and other objects, as well as to modify the Yonaguni Monument that is now found underwater. Even if it is a primarily natural structure, it may have been reshaped to serve as foundation for stone, timber, or mud buildings that have since been destroyed. Or it may have even served as some form of boat dock for an early seafaring people.
I believe that the art and architecture of the area may have been influenced by the natural geomorphology of the Yonaguni Monument and similar structures. There may have been a complex interplay between nature and artificiality, natural forms and man-made structures, in very ancient times. Perhaps rather than being the work of humans per se, the Yonaguni Monument directly influenced the art and architecture of humans some 8,000 to 10,000 years ago, thus helping to initiate a stylistic tradition that continues to this day.
Over the last few years, Professor Kimura has perhaps softened his position somewhat regarding how much of the Yonaguni Monument is "man-made" or "artificial" and how much is "natural." Most recently Dr. Kimura has been referring to the Yonaguni Monument and related structures as being "terraformed," that is natural geological features that have been manipulated or modified by human hands. This is essentially the position that I have come to, so perhaps Dr. Kimura and I are converging in our opinions of the Yonaguni Monument.
If there is evidence of some human modification of a natural structure off the coast of Yonaguni Island, why were the people of ancient times so interested in this particular spot? One suggestion is that 10,000 years ago Yonaguni was located very close to the Tropic of Cancer. Today the Tropic of Cancer is located at approximately 23 degrees 27 minutes north latitude while Yonaguni Island is located a full degree further north. However, the position of the Tropic of Cancer varies over the millennia, from under 22 degrees to over 24 degrees, according to a 41,000 year cycle. In about 8000 B.C. the Yonaguni Monument was located very close to the Tropic of Cancer. Perhaps it was the site of an astronomically-aligned shrine. In conclusion, based on my preliminary reconnaissance of the Yonaguni Monument, I am not yet absolutely convinced that it is an artificial structure - - but in my opinion, even if it is primarily natural, it may have been modified by human actions in ancient times. This enigmatic structure merits more detailed examination."
( i rest my case )
