Today, we began coring Rano Raraku, the crater lake around which almost all the moai were carved. Rano Raraku has been cored more than any other lake on the island, partly due to interest in the statues and partly because it yields beautiful sediment cores. Most of all, access is easy.
For us, Rano Raraku meant a contrast from working in the open on a floating vegetation mat. We were cooped up on a very small raft for the entire day. Today's photo shows a silhouette of David efficiently operating the corer. In the background, you can see the open 9-10m core and 9m of core neatly stacked in boxes.
We'll be continuing to collect sediment cores from Rano Kau for the rest of the week. So far, it looks like we're achieving promising results. Today's picture shows a nice 50 cm sample from one of our two devices. It shows some good layered sediments, as well as some fibrous vegetation that was dragged along on the outside of the corer.As you can see from David's shirt, this is a grimy job. When done well, it produces excellent results.
Today we began our efforts to core Rano Kau, the massive crater lake at the southwest end of Easter Island. Getting there is a challenge in itself. The walk down to where we are coring is a descent of 300m across boulder slopes and then out onto the floating mat that covers the lake.
Our first hole reached 20 meters below water level. Like most previous work in Rano Kau, we found entirely organic sediments (today's second photo shows an ideal sample from deep in the core). These organic layers are derived entirely from vegetation. We were pleased to find the organic layers interrupted by at least two layers of clay, silt and fine sand that may indicate ancient landslides from the crater rim.
This morning we went back up the biggest mountain on the island to do a better job with a couple of samples we'd collected on Wednesday last week, but discovered had some problems when we looked at them carefully over the weekend. In both cases we had to make some impromptu modifications to our gear to get past problems we encountered in the local soils and sediments. In the late afternoon we had just enough time to sample a buried soil profile that was uncovered during quarrying activity recently, and pointed out to us by Charlie Love, a long-time researcher here.
Because it is in a quarry, this set of profiles is very unique -- it goes on for perhaps 50 meters and gets better and better as you walk. The most immediately striking part is that a basalt flow covered a soil, and baked the underlying soil to a bright red color. A new soil, of perhaps 30-40cm thickness has formed on top of the basalt flow. At the very bottom is another soil forming on top of a whitish rock layer (tuff).
||Underneath the basalt flow, we can still see many of the features of the underlying soil. The most remarkable is the preserved structure of the root cavities of the extinct palm which once dominated the landscape here. In the photo that shows extra detail, you can see the root traces as black lines. We think the black color is a manganese mineral that forms around roots as they consume oxygen from the soil.|
We sampled an area that has even more buried soils than you can see here. We hope to be able to identify the plants that grew in each soil and to find out if the plants changed over time. Finally, remember you can look at larger versions of the photos by clicking on them.
Many people have asked about Easter on Easter Island. It's one of the big holidays scheduled around traditional Polynesian culture, but it is an important holiday to the people. It seems to be an important weekend for families to spend together. It seems the main things going on were the usual activities in town, plus an organized soccer game, and earth-oven feasts (which I believe are similar to hangi in New Zealand).
Some of us checked out the main service at 9 am in the Catholic church. The church itself is a very interesting feature of Hanga Roa, the main town. It stands at the top of the hill on one of the two main streets, and displays a combination of traditional Christian and Rapa Nui motifs. The sharp green glyphs on the front of the church are the Rongorongo script, a unique and mysterious form of writing that seems to have been invented by the islanders around the time the moai- building era ended and Europeans first arrived.
The church is always overcrowded on Sundays, with tourists flowing out the doors. As you can see in today's photos, Easter was no different. I've also included a snapshot that shows the inside of the church, including wood carving which are done in the same style as much of the native woodcarving which is on display (and for sale) all over the island.
Radio New Zealand's Easter Monday show called to ask me about Easter on Easter Island - you can listen at this link.
Today my colleague, John Flenley, gave an informal evening lecture to half a dozen Earthwatch volunteers who are visiting the island to assist with archaeological investigations. I joined the the audience, which also included the Chris Stevenson, a Virginia archaeologist, and Thegn Ladefoged, an archaeologist from Auckland University.
In his talk, John reflected on his 30+ years of research on Rapa Nui.One of his themes was the relevance of the scientific investigations of past environments and past human activity on the island to modern civilization. As John puts it, given the potential catastrophes facing the Earth's now globalized civilization, wouldn't it be nice if we could do an experiment to isolate a population of perhaps a few thousand people for a millennium so that we could better understand what can undermine efforts to achieve a sustainable society?
Of course, the civilization that developed on Rapa Nui is as close as we can get to this notional experiment. Before you think further about the experiment, look at today's picture and imagine yourself as part of the isolated society isolated on this small but diverse landscape.
John's point is that we have a lot to learn from this experiment. There is much more to be learned from detailed investigations - including both our study and the one Stevenson and Ladefoged are carrying out to understand the functioning of the gardens that fed people for perhaps a millennium here. There is also much to be learned from integrating the knowledge that has been gathered so far. As we do this, and incorporate more and more detailed information, the story does change. For example, we all agreed that despite most published information pointing to a "collapse" at the the end of the moai- building era, there is a lack of sound evidence that population crashed exactly and dramatically at this time. Perhaps our project will shed some light on this.
In closing, John emphasized that many of the most remarkable things we learn from deciphering the Rapa Nui experiment center around the ways the island's leaders cultivated the moai-building and Birdman rituals to maintain peace between the many tribes/clans on the island. He also notes that the focus of the rituals seemed to shift appropriately from the extremely resource-intensive moai building to a reemergence of the creator god Make Make, as resource issues related to deforestation (and presumably maintaining food production) became a dominant source of concern for the society.
Since he has retired from his role as Professor and head of Geography at Massey University, John has been putting most of his time into efforts within his Anglican church and several trusts to conserve and restore the natural world, both around New Zealand and around the world. He's also just completed work on the third edition of a book on Easter Island, which he writes with archaeologist Paul Bahn.
Since the National Park requires that we take a guide with us each day, and our guide's preference was to spend the Easter weekend with his family, both Friday and Saturday are all about checking the samples we've collected, cataloguing them and getting ready for next week.
I'll take a moment today to write briefly about a couple of the things that surprised me when I arrived here. First, there are a lot of horses. Horses (along with cats, dogs and chickens) are everywhere. They often turn up right in the center of town grazing any scrap of grass, whether it be tiny or the playing fields. Many people, especially younger males, ride horses for transportation. I'm told many of the wild horses were originally placed here to provide a horse breeding ground for the Chilean military. Since the horses are wild, some are not so energetic. The horses in today's picture decided that the middle of main street might be a great place for a nap in the afternoon sun.
This brings me to a second surprising fact. There are a lot of cars, motor scooters and traffic. A native anthropologist, Sergio Rapu, told me today that there is a car for every 1.8 people now. Many are rental cars for tourists. Motorbikes of various sorts are also very popular with locals and tourists alike. As a result of a recent fatal accident, helmets have been required as of April 1. We've been seeing the police all around town enforcing the new law.
At long last, our research team is hard at work gathering samples. We had an extremely effective first day, knocking out what I expected would take several days. I was focussed on sampling rather than taking photos, so I realized I ought to snap a photo for the blog just as I was leaving our last site in the afternoon. This is the highest elevation crater on the island, Rano Aroi. The vegetation is typical of the extensive peat deposits in wet craters here. These peat deposits accumulate dead vegetation layers, and provide an environment that very effectively protects pollen and other organic matter from decomposition. The pollen has proven to be an excellent indicator of past plant populations living upwind of the crater.
Yesterday and today, we collected some dryer sediments that appear to have accumulated over hundreds or thousands of years. In these areas, soils were forming as the sediments were accumulating. Recognizing soil formation processes plays a critical role in allowing us to identify samples that are suitable for our study.
Today's picture shows a sequence of samples that I've pulled up in coring device that takes very small samples -- 1.7 cm in diameter. They are from a soil that was about 1 meter deep, and ended in contact with rock. It was in the center of a small depression in the landscape, near the top of the largest mountain on the island. Each of the 7 samples below is representative of a horizon or layer. Taken together, they show that a soil formed here to a depth of about 50 cm, and then was buried under another 50 cm of soil. Each horizon is represented by one intact 2 cm section in the photo, and is given a
standard letter designation (I won't bore you with the explanation of what each letter means).
A This is the "topsoil". It is dark in color and has a crumb structure. Roots are abundant.
AB This layer still has mainly a crumb structure, but is a bit lighter and has a few less roots.
BA This layer shows some dark areas of the above layers, but has fewer roots and is mainly composed of an accumulation of yellow clay.
Bt This layer is dominated by reddish-yellow clay, which has accumulated in "films". These films are thick and dominate the sample. This clay has moved down from the surface soil, and has been deposited here. This type of clay provides strong evidence of soil formation processes.
2Ab Here we have a second topsoil, which has been buried. It has similar structure to the topsoil above. While it is not as dark, it is still brown rather than red or yellow in color.
2Bt This second layer of clay accumulation shows similar films and color to the layer above -- the color is even more pronounced. This layer suggests that the buried soil was stable for a long period.
2C At the very bottom of the profile, the corer brought up rock fragments (reddish) in a matrix of clay. This represents soil forming from the rapid weathering of the underlying rock.
I found soil profiles very similar to the above in 2 more locations, and all 3 were close to a wetland area the rest of our team was sampling. These profiles suggest a period of stable soil development (perhaps under pre-Polynesian forest) and then a period of rapid deposition that must have been fueled by erosion of the surrounding landscape. It may be reasonable to guess that the upper 50 cm of soil accumulated as a result of agriculture. Confirming this timing will require further analyses back in the lab. But if the buried soil represents pre-Polynesian forest and the upper soil contains evidence of agriculture, then both will contain microfossil and chemical information which will help us understand nearby wetland samples.