Suggested field trip: Visit Jomon obsidian island – Kozushima Island

“Although it is difficult to document trade interactions during MIS 3, obsidian from sites dating to 30,000 BP situated on the Kanto Plain in Honshu, Japan has been sourced to Kozushima (Ikawa-Smith, 2008). Kozushima is an offshore island that would have been minimally separated from Honshu by at least 40 km of open water during glacial periods.

During MIS 2, there is evidence that obsidian was moved upwards
of 300 km from Hokkaido to Sakhalin as early as 23,000 BP (Kuzmin
et al., 2002). “

— C.J. Bae, K. Bae, “The nature of the Early to Late Paleolithic transition in Korea: Current perspectives”  / Quaternary International 281 (2012) 26e35. The article excerpted below takes readers on a trip to explore the prehistoric obsidian island.


The dark allure of an obsidian island ( Yomiuri Shimbun, May. 13, 2012)

Yoshitaka Tsujimoto

KOZUSHIMA ISLAND, Tokyo–“Oh, my lord! They’re so amazing!” I couldn’t help but murmur as I gazed from the deck at waves that crashed against the ship. By “they,” I meant the Jomon people who lived in Japan during the Jomon period (ca 10,000-ca 300 B.C.).

Obsidian–a dark natural glass formed by cooling molten lava–is found in only a handful of places in Japan. During the Jomon period, the rock was used for knives and the points of spears. Kozushima island, located south of the Izu Peninsula, has some of the highest-grade obsidian in the nation, and the useful, beautiful glass has been traded on the mainland since the Paleolithic age more than 20,000 years ago.

Even so, it seems foolhardy to travel 50 kilometers over rough seas in a dugout canoe from the Izu Peninsula just to get it.

I boarded the ship from Takeshiba dock in Minato Ward, Tokyo, to figure out why the Jomon people were so passionate about the obsidians on the island.

Upon approaching Tako Bay on Kozushima island, I saw a cliff comprising layers of obsidian several meters tall.

I visited the village’s history museum, which displays huge chunks of obsidian mined from a seabed near Onbasejima island about five kilometers off Kozushima. The color of a cross-section of the block was as black as the inside of a well. Another thin cracked piece was transparent. I really coveted the piece.

The ship did not sail to Onbasejima because of bad weather. However, on Kozushima, stones in five colors, including obsidian, are spread out on the Nagahama beach.

“The beach is located in front of Awanomikoto Shrine. So you’ll bring a curse on yourself if you take those stones home,” said Misayo Shiga, 65, a part-time staffer at the museum.

Some tourists have sent back stones they took after falling ill once they returned home, she said.

I rode to the beach on a rented bicycle.

This tiny island, which has a circumference of 22 kilometers, has many rolling hills–so a bicycle comes in handy for getting around. The 572-meter-high Mt. Tenjo sits at the center of the island.

When I picked up one of the black stones on the beach, I was warned by an islander: “No one on this island takes stones from the beach. The one enshrined [in Awanomikoto Shrine] is a goddess, and she is greedy.”

OK, I gave up. According to a village legend, the island is known as “kami atsume no shima,” or an island where the gods who created the Izu Islands gather. I have to respect them, especially since so many get together and stay on the island.

I biked up north to arrive at the Akasaki promenade. The walkway made of white wood snakes along the cliff, a strange sight to behold. The waves here are calm as rocks form a kind of breakwater.

I met a fisherman in his 60s while strolling along the promenade. He introduced himself as Umeda.

When our conversation turned to alfonsino–the island’s most commonly caught fish–Umeda said, “That fish doesn’t taste good, so fishermen here don’t eat them. We used to throw them back.”

Umeda and other fishermen like him must have discriminating palates from eating fresh seafood on a regular basis.

“Takabe [yellow-striped butterfish] is the best. You should come back in the summer,” Umeda said in a clipped accent.

Once I returned to the inn, I was served alfonsino cooked in soy sauce. The salty-sweet, strong flavor tickled my taste buds. After cycling around the island, the dish was really tasty!

In its long history, the island once admired by the Jomon people was also a penal colony.

Early the next morning, I visited a huge white cross on a hill overlooking the village. The cross is a monument to a Korean woman with the Christian name Julia. She was exiled to this island for refusing to convert at a time when Christianity was banned in Japan.

Masahiro Maeda, 62, a former section head of the village’s board of education, visited the inn right before I left. Shiga, the guide from the history museum, seemed to have mentioned me to him.

After telling me about the long history of Kozushima, Maeda handed me a small round piece of obsidian.

“This is from Onbasejima,” he said.

It was like a souvenir from one of the gods on the sacred island.


Travel Tip

From Takeshiba dock in Minato Ward, Tokyo, it takes 3 hours 45 minutes by high-speed jet boat or about 12 hours by large passenger ferry to reach Kozushima island. Ships also leave regularly for the island from Yokohama and Shimoda, Shizuoka Prefecture. By air, it takes about 35 minutes from Chofu Airport in Chofu, western Tokyo, to Kozushima island.

For more information, call the Kozushima village tourism department at (04992) 8-0011 .


2 responses to “Suggested field trip: Visit Jomon obsidian island – Kozushima Island

  1. Do you have pictures from this trip?

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