Eerie Island : Strange Formations on San Miguel Are Mineral Ghosts of Long-Dead Trees

Sixty miles off the coast stands a ghostly forest like no other in the world.

On wind-swept San Miguel Island, the western-most island in the Channel Islands National Park, is the caliche forest, an ancient arrangement of twisted white stalks that took 10,000 years to grow.

Hardly the verdant and teeming scene one might imagine, this forest instead is reminiscent of a chalky graveyard littered with skeletal shapes, the casts of trees that disappeared eons ago.

“This is one of the few places in the world where you can see that kind of formation,” said William Halvorson, research biologist for Channel Islands National Park. Caliche can be found in other arid climates. But the forest on San Miguel is unique, he said.

It began as a green forest, most likely made up of conifers like the Douglas fir that flourishes in cold mountain climates. As the Earth’s climate slowly warmed after the last ice age, which ended 600,000 years ago, the trees died out, Halvorson explained.

Blowing sand and soil gradually covered the trees to a depth of 30 feet. The combination of rainwater and calcium carbonate, a mineral compound found in the soil, reacted to form caliche. Caliche is a brittle deposit that hardened to make casts around the trees and their roots, a few 12 feet tall.

Because the rainwater seeped downward into the soil, only the lower portions of the tree trunks and their roots were surrounded by caliche. Gradually, the organic matter of the trees rotted out, leaving only the rough casts now exposed by wind and erosion.

“It’s a one-of-a-kind thing,” Halvorson said. “If it’s destroyed, it cannot be rebuilt.”

Now the caliche forest faces a new test, one not encountered during 10,000 years of rain and wind.

Part of the National Park Service mission is to bring more people to see the wonders of San Miguel and its skeletal forest. But increased tourist activity conflicts with another, more important mission of the park: preservation of the island’s natural state, said park Supt. Mack Shaver.

Among the resources that must be preserved, Shaver said, are the caliche forest, the sparse native vegetation and the few native island mammals. Also, up to 100,000 elephant seals and sea lions come to breed every year.

But visitors, no matter how careful, bring disturbance, Shaver said. Each trek through the caliche forest, no matter how carefully plotted, causes more of the ancient remains to crumble into the sand.

“It’s a trade-off,” he said.

The Park Service will monitor the impact of visitors over the next few years, Shaver said, to determine what number can be safely accommodated.

Only 500 people visited the island last year, Shaver said, although park officials hope that figure will increase. The island’s distance from the mainland and its rugged terrain will prevent tourists from overruning the site, Shaver said.

“We think the island can handle the demand,” he said.

The fragile caliche forest is found on 500 acres of the Central Dunes, the inland part of the 14-square-mile island.

There, atop bleak white dunes, two-foot-tall, jagged mineral castings of once-living tree trunks jut from the sand-scape. Shaver said he has seen in a wind-protected canyon a 12-foot-tall caliche formation that was two feet in diameter. The shapes are so fragile that even a light brush can topple them.

Here and there, 20-foot-long lace-like formations stick out of the ground, revealing ancient root systems that once sustained the trees.

Strewn across the sandy floor are scores of hollow tubes about three inches long, remnants of twigs from the branches of prehistoric, mighty trees.

Like brittle pottery, the twigs clink when caught underfoot. In many places shattered casings can be seen, the result of the destructive effect of harsh island weather and, possibly, of foraging by animals.

No one is sure how old the caliche forest is, Halvorson said, but estimates are 8,000 to 10,000 years.

“It’s not like having a tree you can count rings on,” he said.

As sparse as the caliche forest is, the rest of the island offers little more.

The tallest growth is about 20 willow trees that Halvorson said are hidden in wind-protected canyons, and four palm trees left by a film crew that used the island as a setting for a version of “Mutiny on the Bounty.”

Ranchers on the island before it was acquired by the U.S. Navy, which still holds title, once maintained sheep and burros there. The animals were rounded up in 1977.

Because there was very little grazing in the caliche area, Shaver said it is unlikely the animals caused the destruction that can be seen in some parts of the forest.

The sensitivity of the caliche forest is part of the reason the Park Service requires a ranger to accompany visitors to the island, said Shaver, who recently led a group on a 12-mile hike across the island’s rugged terrain.

To attract more visitors to the island, the park has opened San Miguel to overnight camping, but visitors must get permits from the Park Service office in Ventura in advance. Overnight visitors are allowed Memorial Day through Labor Day only.

Camping accommodations are primitive, providing little or no shelter from the constant 20-m.p.h. winds.

Island Packers, a Ventura firm, holds the concession to take visitors to San Miguel on a three-hour trip by boat. Channel Islands Adventures offers half-hour flights to the island, where pilots land on one of two dirt strips, for slightly higher fare.

Visitors can sail to the island, but guidebooks warn that the rock-filled, rough waters around San Miguel are a “graveyard of the Pacific” because of the large number of ships that have wrecked there.

The ranger who meets every group is charged with seeing that visitors stay on established paths to prevent the destruction of the caliche forest and the island’s other resources.

If the Park Service is prudent with its unique resource, the caliche forest will remain a monument to the past for many generations, biologist Halvorson said.

“If it’s protected, the caliche will last hundreds, if not thousands of years,” he said.