Tawara Island

Tawarajima: A Basalt Islet of Stacked Stone Columns in Nagato

Off the southwestern shore of Yuya Island, near the far end of the Mukatsuku Peninsula in northern Yamaguchi Prefecture, a small island stands roughly 100 metres out in the bay. It rises only about 30 metres above the water and measures some 500 metres around. What sets it apart is its material: the whole of Tawarajima is basalt, lava that erupted about 8.5 million years ago and cooled into a dense pack of stone columns.

Seen from a boat or from the cliffs of Yuya Island, the columns lean every which way. Some stand upright like a fence of posts. Others tilt, lie flat, or curve in a slow arc. The reddish-grey rock, flecked with small dark crystals, looks less like a natural outcrop than a stack of goods left on a wharf. That impression gave the island its name. Tawara is the woven straw bale once used to carry rice, and the heaped columns suggested bales piled on their sides and ends.

How the Columns Formed

The columns are a textbook case of columnar jointing. When a thick body of basalt lava cools, it contracts, and the shrinking rock cracks into a network of joints. Where conditions are even, that network resolves into polygons, and the rock splits into long columns running at right angles to the cooling surface. At Tawarajima each column is about 35 to 45 centimetres across, with a cross-section of four to six sides.

There is more to the island than the basalt above the waterline. Beneath it lies an older Tertiary layer of sandstone, conglomerate, and shale. Wedged between the shale and the sandstone is a band of limestone roughly two metres thick, built almost entirely from the remains of Lithothamnium, a calcareous red alga. The survey that led to the island's protection singled out this limestone, recording that the structure of the algal fossils was unusually distinct, with few comparable exposures known elsewhere.

The sea has done its own work. Waves following the lines of the joints have cut hollows and small caves into the rock, and on rougher days the swell of the Japan Sea drives against the cliffs in a way the early survey described as a striking sight.

Why Tawarajima Is Protected

Tawarajima carries a double designation. It was first listed in 1927, under a notification of the Home Ministry, as both a Place of Scenic Beauty and a Natural Monument. In 1959 the protected area was enlarged to take in additional ground.

The two labels point to two kinds of value. As a Natural Monument, the island is significant for its geology: the clarity of the columnar jointing, the way the rock and its joints are organised, and the fossil-bearing limestone below the basalt. As a Place of Scenic Beauty, it is valued for the sight itself, a small island whose every surface is ordered into columns, set against the shifting water of the bay.

What to Look For

The most rewarding view is from slightly above. Walk to the west of the small lighthouse on the headland and look down at the cliff face. Across a span of a dozen metres or so, the joints show their cut ends all at once, a field of four- and six-sided cells packed together like a honeycomb.

This is a place to slow down. The columns are not uniform. Following one with your eye, you find it bending where the lava cooled unevenly; beside it, a neighbour lies almost horizontal. The play between order and irregularity is the whole character of the island, and a photograph rarely captures it as well as a few minutes of standing still.

From the water the island reads differently again. The southern face, toward Yuya Bay, stays calm enough for a boat through much of the year, and from there the columns rise straight out of the sea.

Getting There

Tawarajima sits at the end of the Mukatsuku Peninsula, and reaching it takes some effort. From Hitomaru Station on the JR San'in Line the drive is about 30 minutes; by public transport, a bus runs toward Oura, from where the rest of the way is a long walk. The final approach leaves the road and drops down a narrow track between fields to the beach.

From the shore a line of placed stepping stones leads out to the islet. At low tide the crossing is straightforward, though one stretch of the stones has given way and you may need to wade. At high tide the island is cut off. None of this is required to enjoy the site, since the columnar rock is clearly visible from the beach and many visitors look rather than cross. There is no admission charge, no staff, and no facilities, so water and proper footwear are sensible.

Around the Peninsula

The Mukatsuku Peninsula rewards an unhurried drive. About four kilometres back toward the mainland, the Yang Guifei Memorial Park draws on a local legend that the celebrated Tang-dynasty consort came ashore on this coast. The nearby temple of Nison-in keeps two seated Buddhist images, a Shaka and an Amida, both dating to the Kamakura period and both designated Important Cultural Properties.

Further along the same coast, Motonosumi Shrine sends a corridor of vermilion torii gates down a grassy slope toward the sea. Above the shore nearby, the Higashiushirobata rice terraces fill with water in early summer, and at dusk the flooded paddies hold the colour of the sky.