MAHAULEPU — On Kauai’s Southside lies a sinkhole at Makauwahi Cave Reserve.
If that doesn’t sound important, it is.
Chris Landreau, a local archeologist, calls it “greatest scientific place in all of the Hawaiian Islands.”
“What we have here is so special,” he said. “It is such a unique place because it offers the only unadulterated view of the last 10,000 years. It is the clearest view we have into the past.”
Dr. David Burney, a paleoecologist at the National Tropical Botanical Garden and manager of Makauwahi Cave Reserve, calls it a “poor man’s time machine.”
And guided by the fossil evidence buried in the cave’s sediment, the reserve is working to re-vegetate the area with native plants.
Half a million years ago, a large sand dune turned to limestone. As time went by, freshwater carved into the stone, creating an underground maze of caverns. Then, 7,000 years ago, during a warm period in the Earth’s history, the roof of the cave’s largest chamber collapsed. The sinkhole eventually filled with water, and animals and plants that washed in fell to the bottom, where they were perfectly preserved.
“We have soils for 10,000 years that we know of all the way to the bottom, to the bedrock,” Landreau said.
That 10,000-year period of the island’s history is contained in just 30 feet of sediment.
While digging, scientists have documented records of floods, droughts, a massive tsunami, hurricanes and the living and dying of the island’s plant and animal species. They’ve been given a glimpse into the different stages of human history here, from the first Hawaiians up to present day.
It’s all in the layers. They deeper you dig, the further back in time you go.
The most amazing discoveries, in Landreau’s opinion, include the bones of extinct animals, particularly an endemic and flightless duck, the moa-nalo, and a giant owl species that measured upwards of 3 feet tall.
“We can see all of the changes, large and small,” Landreau said. “All the little forest birds that we think live up in the forest, you know, the creepers and stuff? There’s evidence that some of that was down here too, and they’ve been driven up there by the rats, the pigs, the people.”
Landreau and Assistant Reserve Manager Linz Armstrong recently gave The Garden Island a tour of the reserve. The archeologists become visibly excited when talking about the area and its unique ability to capture time.
“We’re finding pieces of gourd that are six, seven hundred years old,” Landreau said. “Gourd doesn’t preserve at all. It doesn’t preserve more than a week. If you left it out here, gourd would disappear.”
In the cave, not so much.
Like other discoveries, the gourds, which were brought to Hawaii and planted by the Polynesians, provide direct evidence of the people who were living on the island.
Amazingly, the best preserved materials are those in the clay material at the very bottom.
“It has never touched air since it went down there,” Landreau said. “The neutral environment has impeded almost all disintegration. So you find plant remains — like grasses and things like that, plant remains, leaves — 10,000 years old.”
It’s a perfect “Goldilocks Zone” for archeologists — the “greatest preserved place in all of Hawaii,” Landreau said.
For that reason, he and Armstrong consider themselves among the luckiest in their field.
“Archaeologists dream of this,” said Armstrong, who first came to visit the cave as an archeology student. “I just fell in love with it.”
Currently, there are no active digs going on. However, over the years, objects and artifacts pulled from the upper sediments have included fish hooks, gourd stoppers, loads of fish and bird bones (staples of the Native Hawaiian diet), nuts and seeds, corals, sea urchins, pieces of canoes, iron nails — the list goes on.
Chambers of the cave, which connect with underground lava tubes, are also home to some of Hawaii’s rarest creatures, including shrimp-like amphipods and their predator, an endangered species of blind cave wolf spiders.
While the sinkhole is the main attraction for visitors, the 17-acre reserve is about much more — the re-wilding of Kauai.
Using what’s been unearthed in the sediments as their guide, the team at the reserve is revegetating the area with native species once part of the landscape.
On six acres of abandoned farmland locals call “Lida’s Field of Dreams,” the reserve is experimenting with native plant restoration. Where weeds once grew out of control, native trees and shrubs have been re-established.
Perhaps the reserve’s most important tool in the fight against invasive, aggressive weeds? Giant African spurred tortoises.
“They eat the weeds,” said Armstrong, as he scratched one on the neck. “And what they tend to do is leave our native plants alone.”
Today, the property is home to 20 tortoises, which roam fenced-off portions of the area.
The native plants produce a hefty seed crop each year that is harvested for use in other native plant restorations.
In a single year, more than 5 million native-plant seeds of about 40 species were harvested for use in other restorations, according to the reserve’s website.
Not surprisingly, visitors come in flocks. On any given day, if the gate to the sinkhole is open, there might be 40 to 50 random visitors, people who just happen to be walking by. Last year, 23,000 visitors came and went.
It is not a money-making business by any means.
“Essentially the mission of this is scientific rediscovery,” Landreau said. “Basically we want to restore the native plants and animals as well as we can from what we learn in the soil and in the sediments. So all the fossils that we collect, all the plant species, it’s all to sort of teach us what Kauai once was and do our best to do some restoration work around it.”
Makauwahi Cave Reserve is a nonprofit organization with Garden Island Resource Conservation and Development Inc. as a fiscal sponsor. The property is owned by Grove Farm Company, and managed by Lida Pigott Burney and Dr. David A. Burney, with the help and support of thousands of volunteers, students and visitors from the local community and around the world.
Guided tours are led every Wednesday, Friday, Saturday and Sunday, from 9 a.m. to 2 p.m. Info: www.cavereserve.org.