The Earth Story

Tafoni Basalt This is a lovely rock from Rapa Nui (aka Easter island). Like many of the rocks on that hotspot-produced island, this rock is a basalt, a lava flow erupted from an oceanic volcano. You can also clearly see how the outermost layer of the rock is being gradually popped off – this honeycomb like texture is called “Tafoni” by geoscientists.

Subducting a rise The Nazca plate is mostly formed at the East Pacific Rise oceanic spreading center and consumed as it is subducted beneath South America, forming the modern-day Andes mountain range. At one point on the East Pacific Rise, a hotspot sits at the same place as the ridge, creating much larger underwater volcanoes than elsewhere on the plate. Some of those volcanoes even reach the surface, including Easter island.

Original caption:

Easter Island

Ranu Kau volcanic crater at the tip of Easter Island

The southern tip of Rapa Nui (Easter Island) is a volcanic crater called Ranu Kao. It is filled with a number of small lakes, and the ocean is just beyond the crater wall. Really great shot of it here - literally inside a volcano.

RAPA NUI: EASTER ISLAND

The mysterious Isla de Pascua (Easter Island) is one of the most isolated inhabited places in the world. A territory of Chile, the 163 square kilometer island is located 3,512 kilometers from the nearest point in South America. The closest island is Pitcairn Island, 2,075 kilometers away. Easter Island is most famous for the numerous human-like moai statues and other archaeological rock formations found on the island. It also serves as an example of the damaging effects of deforestation, drought and overuse of natural resources.

The island was settled by Polynesians some time between 700 to 1200 CE. It gets its name from Dutch explorer Jacob Roggeveen, who discovered the island on Easter Sunday, April 5, 1722. The Polynesian name for the island, however, is Rapa Nui, or Big Rapa, named after the island of Rapa in the Bass Islands group which has the same general shape.

Easter Island is volcanic. Three large volcanoes give the island a somewhat triangular shape. The island is part of a volcanic chain that formed as the Nazca Plate floated over a mantle plume known as the Easter hotspot. A hotspot creates a string of islands and seamounts as a tectonic plate moves over the top of the mantle plume. The Hawaiian Islands is another example of an island chain formed by a hotspot.

The Easter Island moai statues were carved out of volcanic ash, or tuff from the Rano Raraku volcano. The inhabitants used hand tools and chisels to carve the 887 statues, which average about 4 meters tall. The largest, Paro, is 9.8 meters tall and weighs 74.3 metric tons. Almost half the statues still remain at the quarry. Mystery still surrounds the statues, as the people who carved them were nearly wiped out by famine from drought and soil erosion, war, disease, and slavery. When discovered in 1722, the estimated population of the island was around 4,000, and by 1887, just over 100 islanders remained. In recent times, the population has climbed back to nearly 4,000. Much of the history and traditions of the early inhabitants have been lost.

-Amy

References:

http://www.eisp.org/120/

http://blogs.scientificamerican.com/history-of-geology/2011/10/31/climate-overpopulation-environment-the-rapa-nui-debate/

http://petrology.oxfordjournals.org/content/38/6/785.full

http://archive.cyark.org/rapa-nui-info

See our past Earth Story article about Easter Island: (November 27, 2012)

http://tinyurl.com/cpxcxrb

Image of a moai quarry on the slope of the Rano Raraku volcano, Easter Island courtesy of Rivi, Wikimedia commons

http://commons.wikimedia.org/wiki/File:Rano_Raraku_quarry.jpg

Mysteries of Easter Island - Beautiful Moai (Part III)

Easter Island, one of the most remote, inhabited islands (see, http://bit.ly/1ENQBO8 and http://on.fb.me/1fEelhd) in the world is located over 2,000 miles off the coast of Chile. The giant stone heads, Moais, of Easter Island are a fascinating mystery. The statues are thought to be the faces of the ancestors of the Rapa Nui people that carved them sometime between 1250 and 1500 CE. Why were the stone heads built in the first place? Who put them there? Is it the aliens? These questions have perplexed people for hundreds of years. Researchers are excavating the statues (in the picture) to better understand the Rapa Nui people and to explain the secrets of these beautiful Moais.

For the first time in 2012, it was confirmed by researchers working in the Easter Island Statue Project (EISP) that the "famous heads" of Easter Island Moais also have torsos buried within the soil. Archaeologists have always suspected that the Moais have torsos after finding half finished and broken statues strewn near the island's stone quarry, Rano Raroko, but recent on-site excavations confirmed this result. Jo Anne Van Tilburg, director of the EISP, believes the 150 most fascinating, famous and widely recognised Moais are "buried up to the shoulders on the slope of a volcano, and this suggested to people who had not seen photos of (other unearthed statues) that they are heads only."

The Moais are believed to be most amazing works of art by Rapa Nui which not only showcased their excellent aesthetic sensibilities but also their epic endurance. According to the local legend, the ancestral spirits (mana) were invoked in the statues by Rapa Nui and then the statues were walked from the center of the island to the beach. The experts are of the opinion that Rapa Nui had used sheer physical prowess and skills both in building the huge monoliths and then successfully transporting them to their pre-designated locations near the sea. A simple number will be enough to explain the islanders' Herculean feats; the tallest head discovered to date is over 9 meters (30 feet) tall and weighs about 74,390 kgs (82 tons). The torsos of the statues are covered with petroglyphs; drawings believed to represent an ancient pictographic written language of the Rapa Nui people. The EISP researchers found many crescent shaped symbols, most likely depicting the canoes on which the islanders came to the island. They are now studying the designs on the Moais to decipher the language of the Rapa Nui people. Van Tilburg is confident that the excavated torsos will provide them with new information about the Rapa Nui and will help them get a glimpse into the lives of these people.

--RB.

Further information: http://bit.ly/1J9bfxY http://bit.ly/1fVc4iw http://bit.ly/1CPWb73 http://bit.ly/1JqBv2z http://dailym.ai/1hGy9uv http://bit.ly/1JCU9bx Image: http://bit.ly/1CPQPbU

Mysteries of Easter Island - death of a civilization (Part II)

The loss of the Rapa Nui civilization (see, http://bit.ly/1ENQBO8) has sparked a great debate amongst experts as to the real reasons for its demise. On one hand, Pulitzer Prize winning author Jared Diamond proposed that Rapa Nui extreme and wanton destruction of nature led to their downfall. On the other hand, archaeologists Terry Hunt, University of Hawaii, and Carl Lipo, California State University, are believers in the ingenuity of Rapa Nui and have argued they are examples of human resilience and endurance against all odds.

John Flenley, biogeographer from Massey University, New Zealand has found pollen sediments in lakes around the island that prove that the area was once a lush forest. Jared Diamond, citing Flenley’s work, believes that once the Rapa Nui landed on the island they started cutting down trees to provide farmlands. "They had the bad luck," Diamond argues, "to have settled in an extremely fragile island—dry, cool, and remote, which means it’s poorly fertilized by windblown dust or volcanic ash." The agricultural yields were not enough to feed all the islanders. As more and more trees were felled for farming and canoe building, forest wood became scarce. At some point there was not enough wood to build canoes and so the islanders couldn't go for fishing. Their food source vanishing led to a civil war and people resorted to cannibalism even before the Europeans arrived.

Archaeologists Hunt and Lipo disagree with Jared Diamond's version and have proposed a different way to explain the loss of the Rapa Nui civilization. According to them, the islanders were not actively at fault for the destruction of their home; instead it was an ecological catastrophe caused by rats. They believe that when the Rapa Nui came to the island, they bought with them rodents from the mainland. In the absence of any natural predators these rats bred prolifically and became a menace for the islanders, destroying their homes. "Feasting on palm nuts, they would have prevented the reseeding of the slow-growing trees and thereby doomed Rapa Nui forest, even if humans hadn’t been slashing and burning. No doubt the rats ate birds’ eggs too," according to Hunt and Lipo.

Finally, a team of researchers from the U.S., Chile, and New Zealand have published a third theory that competes with the other ideas. They used a technique called obsidian hydration to date Rapa Nui artifacts and constructed a timeline of these people's lives over hundreds of years. They found population shifts occurred over time because of changing climate patterns which limited their food sources, and that took a toll on their health. According to them, the population in their weakened conditions became infected with diseases such as smallpox and syphilis that decimated their numbers. EISP researchers are striving to answer which factor contributed more towards the destruction of Rapa Nui.

--RB. More about Rapa Nui: http://bit.ly/1MqvQzM http://bit.ly/1MoLSsV http://bit.ly/1KnJG2E Image: http://bit.ly/1Ii6lJV

Mysteries of Easter Island - Rapa Nui (Part I)

Easter Island, some 3700 kms from the western coast of Chile is one of the most remote inhabited islands in the world. Around 300 AD indigenous Polynesian tribesmen left their homes in canoes in search of a new world and arrived at the Anakena beach. From then until Easter Sunday in the year 1722 (how the island got its name) when Dutch settlers arrived, the local community thrived in a world of their own, sheltered from all the trappings and progress of the new world. Soon after the arrival of the Europeans, they encountered problems like new diseases they were not immune to, slavery, slaughter, and oppression. By the end of the 18th century the population plummeted to 111 individuals. Contact with western civilization, slave trades, and spread of diseases like smallpox decimated the population and destroyed their wonderfully distinct culture, most of it gone forever. While western influence may have hastened their ruination, Rapa Nui were on the brink of becoming a lost civilization for a long time. Some experts attributed their decimation to ecological catastrophe whilst others blame them for bringing their own doom by wanton destruction of nature (discussed in depth in the second part of this series).

The Rapa Nui built shrines and erected enormous stone figures known as moai that represent their ancestors (the subject of the third part of this series). The unique architecture and sculpture of these people is displayed in the scattered moais around the island, and the ahu (ceremonial platform); the most colossal is the Ahu Tongariki with 15 moai. About 900 statues and more than 300 ceremonial platforms are estimated to be around the island; that part of the island is classified as a World Heritage site by the UNESCO World Heritage Centre. There are many caves (ana) and rock art sites around the coast of the island displaying the visually stunning, versatile talents of the Rapa Nui in the forms of pictographs and petroglyphs; also noteworthy is their pictographic form of writing (Rongo Rongo), so far undeciphered. The Easter Island Statue Project (EISP) researchers are working towards unravelling the mystery of the long lost civilization.

--RB. Further information: http://bit.ly/1LA6Aac http://bit.ly/1gRI1bL http://bit.ly/1EDQlRt Image: http://bit.ly/1Ii6lJV http://bit.ly/1elisy0

At first look this photo may appear as pretty standard or boring, when in fact it is rather special. This is Easter Island; it is one of the most remote Islands on Earth. The Island is more than 2000 miles from the closest populations on Tahiti and Chile. This photo was taken by astronauts in the International Space Station in 2002.  What makes this photo special? These astronauts, at 242 Miles above the Earth’s surface were actually closer to Easter Island than anyone else in the World at this time (aside from local inhabitants!). -Jean  Photo courtesy of NASA.

Meet the yeti crab, a creature so unusual that a whole new biological family had to be created to classify it. It was found along the Pacific-Antarctic Ridge, 1,500 kilometres south of Easter Island at a depth of 2,200 metres living on hydrothermal vents. As a result of analysis based on morphology and molecular data, the organism was deemed to form a new biological family (Kiwaidae). But, a lot else remains an enigma and much more is to be discovered. We do know that yeti crabs lack pigmentation in the eye and are hence thought to be blind. Also of interest, their fluffy pincers have been discovered to contain filamentous bacteria which may be involved in a chemosynthetic relationship with the organism. It is suggested that these bacteria may detoxify some of the poisonous minerals emanating from the hydrothermal vents. -Jean Photograph by Ifremer A. Fifis

At first look this photo may appear as pretty standard or boring, when in fact it is rather special. This is Easter Island; it is one of the most remote Islands on Earth. The Island is more than 2000 miles from the closest populations on Tahiti and Chile. This photo was taken by astronauts in the International Space Station in 2002. What makes this photo special? These astronauts, at 242 Miles above the Earth’s surface were actually closer to Easter Island than anyone else in the World at this time (aside from local inhabitants!). -Jean Photo courtesy of NASA.