Rano Kau
Walking Up Rano Kau
One day I walked up to the rim of the
Rano Kau caldera.
It's a little over fifteen kilometers up and back,
starting from the fishing port,
plus further to get to and from that starting point,
plus whatever side excursions you make.
I was fine with the 22 km distance for the day,
but the 300 meter ascent to the crater rim
and the descent back down left me pretty wiped out.
Rano is the Rapa Nui term
for a lake in a volcanic caldera.
The lakes within the volcanic cones of Rano Kau,
Rano Raraku, and Rano Aroi
were crucial for human settlement.
There are no other lakes on the island,
nor are there any large streams.
The island of Rapa Nui is the peak of a volcanic mountain
rising over 2,000 meters from the sea floor.
What protrudes above the ocean are the coalesced peaks
of three extinct volcanos.
Rano Kau, 324 meters tall,
is at the southwest corner of the island,
overlooking the town of Haŋa Roa.
Poike, 400 meters tall, is at the eastern tip.
Terevaka, the tallest at 507 meters,
is near the center.
The fishing port is across from the football field, at the T intersection of Policarpo Toro, the waterfront road, and Te Pito o Te Henua, the street leading up the hill to the Roman Catholic church. The intersection always seemed to me to define the center of town, plus Te Pito o Te Henua means "The Center of the World" and seems to have been the original name for the island. I will start by walking off to the left, following the coast. I will pass the Chilean Navy facility on the point of land in the distance.
Ahu Hotake with a restored and re-erected mo'ai overlooks the fishing port. The sign warns of sea turtles, urging you to leave them alone.
This took me past the Oheho Surf Cafe, just past the end of the football field. I stopped here for a rest and a drink when I returned to town.
Across the waterfront street, the Pea RestoBar has tables just above the water.
Turning and looking back, I could see the standard design of Ahu Hotake.
The mo'ai were installed on ahu, stone platforms that evolved from the traditional Polynesian marae, communal or sacred spaces. On Rapa Nui, an ahu had a central stone platform, and one or more mo'ai were often erected there.
Most of the ahu, like this one, are built with the quite dark basalt that forms much of the island. Most ahu are along the coast, aligned so that the mo'ai, representing specific deified ancestors, stand with their backs to the land of the dead in the sea and looking inland over the settlement of their descendants. With the proper rituals, the living can provide for the ancestors. In turn, the ancestors will use their mana or supernatural force to provide good health, good fortune, and fertility of the land and sea for their descendants.
The central platform slopes down slightly. Rows of rounded sea stones called poro are placed directly in front of the platform.
Most of the ahu on Rapa Nui were destroyed or abandoned when Christianity arrived in the 19th century, but the locations remain tapu or sacred.
Along the Coast
The Chilean Navy has a small communications facility on a point close to the fishing port. Rapa Nui is 3,500 kilometers from the coast of South America, so folded dipole antennas provide long-range HF communication.
I turned to look north along the coast past Haŋa Roa. Terevaka, the tallest peak at 507 meters, is in the distance.
Continuing around the point, I was soon looking at the base of Rano Kau and its cliffs along the coast. The short red and white radio masts as part of the airport. Its 10,885-foot runway extends across the island, almost isolating Rano Kau from Haŋa Roa.
There are more fishing boats in this second harbor. At the center of the picture you can see the small cargo port.
A cargo ship anchors off shore, and uses its on-board crane to transfer containers to two boats that carry the containers to the wharf, where cranes transfer the cargo. That and cargo aircraft are the only way of getting things on and off the island.
A park next to the cargo wharf has Ahu Riata and its lone standing mo'ai, plus a few more lying down.
Walking Up Rano Kau
I walked past the end of the runway, and soon passed the municipal water plant.
Further along, a sign warned that there are sacred ancestral sites in the area.
Te Pito o Te Henua meaning "The Center of the World" was an earlier name for the island. According to the legends, the king who led the settlement voyage had been told of The Island at the Center of the World in a dream.
A cluster of satellite Earth stations and point-to-point and broadcast antennas is along the road. The airport boundary is a short distance off to the left.
Mateveri Airport and the town of Haŋa Roa become visible as the road climbs.
Pou Hoko is around 180 meters elevation, where the road turns sharply.
There's a small mo'ai head there.
The road continues up the volcanic cone. The north side of the volcano is a relatively gentle slope from the rim down to the airport. But it's a slope, you climb up and up as you ascend about 300 meters to the rim.
Amazon 0394800206
It took me a while to figure out what this tree reminded me of. Oh, of course. It's the tree from Go, Dog. Go!
Now if only there were a bunch of dogs having a party all through the branches of this tree...
The road continued to climb, and the airport and town came back into view.
Looking to the right of Haŋa Roa, you're looking along the south coast. Poike is the volcanic cone at the far end of the island, 20 kilometers away.
Visiting Other Calderas
Aso-san, Japan
Kagoshima, Japan
Thera, Greece
Milos, Greece
Valles, USA
Along the Caldera Rim
Soon I reached the caldera rim. The word caldera comes from the same root as cauldron. A caldera is formed when a large lava chamber partially empties and then collapses, forming a broad flat-bottomed area surrounded by a ring wall, looking like a gigantic dish or cauldron.
The lake within the Rano Kau caldera is about 100 meters above sea level, more than 200 meters below the highest points of the crater's rim.
Marine erosion over millennia has eaten away the southwest sector of the volcano, forming cliffs that drop 300 meters down to the sea.
That led to the formation of Kari Kari, a 400-meter-wide notch in the rim where the erosion and cliffs have slowly progressed inland.
Rapa Nui is on the Nazca Plate, which moves to the east about 150 mm per year above a volcanic hotspot or source of magma. That means that Poike, the peak forming the eastern corner of the island, is the oldest, and Rano Kau at the southwest tip is the youngest.
The hotspot is a source of basaltic magma, which has formed most of Earth's oceanic crust. The first eruptions forming Rapa Nui began about 2.5 million years ago. With Rano Kau being the youngest peak, what we see today as its volcanic cone developed over approximately 780,000–450,000 years ago. The last significant eruption was about 180,000 years ago.
So it's extinct, at least for now. In the early 1900s, when the island was controlled by an English sheep-farming company and the Rapa Nui people were forced to live within the town and work for the company, the English manager took a photograph that seemed to show steam issuing from the steep slopes around the caldera.
The interior slopes of the caldera are steep. They're about 45° at the lake shore and steepen to 65° near the rim.
Rano Kau has produced a great deal of obsidian. Pieces lie on top of the ground along the footpath on the caldera rim.
On Rapa Nui you mustn't carry away anything. On Milos, in the Aegean Sea, where there's no such rule and you're actually encouraged to look for obsidian, I saw nearly identical smooth-surfaced black stones lying alongside a gravel track. I put some in a cloth bag and took them back to my room. That evening I was looking at them, thinking "These are supposed to be obsidian, but this doesn't look much like glass to me." And then I noticed that my fingers were bleeding.
Yes, this is what obsidian looks like. And it can be incredibly sharp.
The caldera captures rainwater. The lake or lagoon is about a kilometer and a half in diameter, and is about ten meters deep. Its surface is largely covered by floating mats of totora reeds, about one meter thick.
The three large calderas shelter their interiors from the winds that blow across the rest of the island and maintain higher humidity, forming their own micro-climates. Figs, many vegetables, vines, and other useful plants grow within the calderas. Some are endemic to the island, others were brought by the settlers. Early settlements were established down in some of the calderas. An old settlement with a cluster of petroglyphs has been found down close to the edge of this lake.
The manavai, circular stone enclosures in which the Rapa Nui people maintained gardens, may have been based on the protective nature of the calderas.
The highest point along the caldera rim, a short distance ahead, is 324 meters above sea level.
Here's a different view over the road, the south coast, and on to Poike, 20 kilometers to the northeast.
To the left, Terevaka is the largest of the three volcanic cones, 507 meters high.
Rapa Nui has one of the largest collections of petroglyphs in all of Polynesia. There are around 1,000 sites with more than 4,000 petroglyphs. Here's one at the viewpoint along the caldera rim.
The designs and images served various purposes: creating religious totems, marking territory, and memorializing people and events.
Equalization
Here's the above image enhanced with localized histogram equalization with a radius of 50 pixels.
I made my way back down to town through the shaggy trees.
