Easter Island Blog        

Mission Accomplished?

After G W Bush's "mission accomplished" event on the deck of the
aircraft carrier involved in the Iraq invasion, I'll never utter these
words without a question mark after them. With the question mark
added, they are apt for our last day here. We think we've got a great
set of samples to bring home. The map I'm including shows they're well
distributed across the island. But until we do the work in the lab, we
won't really know if we've accomplished the mission.

I'll try to keep you updated, and there will be at least one more post
about the people we've worked with here.

 
12:35 PM

Tuesday 28 April: Dave's shoes

Dave's idea of packing for a big overseas field trip is to find old
shoes that are about die, and to leave wear them until they die. This
seems risky to me, but at least means he doesn't have to clean them to
get back into NZ.

Today was our last full day on the island, so Dave went for a long
hike. When he returned, he pronounced his shoes to be dead.

 
12:30 PM

Monday 27 April: The last sample

Today we collected our last sample. Keeping with our efforts to find
buried soils, here's another example. This is from 90-120 cm, and the
darkening (that looks just like a good garden topsoil) is at the
bottom, from about 108-120 cm! 
12:26 PM

Sunday 26 April: Mana vai

Today was our "day off" again, which meant we started packing and
writing our report.

I thought I'd tell you about the mana vai which the people of Rapa Nui
used, and still use, to grow crops. Within stone walls, the plants are
well protected from the wind; this conserves water (vai). This is very
helpful for the more tropical plants brought from Polynesia. Here our
guide Soro has ginger in one hand and a sugar cane in the other. Mark
and John were impressed, and there's more sugar cane behind John.

The other photo shows a much tidier mana vai, which we saw in the same
area while we were looking for places to sample soil.

 
12:19 PM

Saturday 25 April: Lithic Mulch

Today we sampled a site quite some distance around the north coast.
Here's a view of our site (with a calf for scale), which contained
about 2 meters of nearly rockless soiI. It took researchers a long
time to recognize that all these rocks were put in place by people to
reduce water losses from cultivated plants. Amazing, eh? 
12:11 PM

Friday 24 April: Refining our target

As our soil sampling has proceeded, we've been able to refine our
visual target for sites. We're trying to find sites that naturally
collect sediment from a significant uphill area with both human
occupation and agriculture. As we've proceeded, our skill has improved
at finding sites that collect sediment efficiently without being
scoured out during major floods. This site was nearly ideal. It
samples a large area upstream of gorge in the background. The exact
location we sampled showed evidence of almost continuous soil burial,
but had to be chosen carefully because areas directly downstream of
the gorge appeared to be scoured out during floods.

In the sample shown, the core is composed entirely of material dark
enough to be a topsoil, but the sample is from 1.2 - 1.5 m below the
soil surface. Throughout most of the island, soils at this depth would
be light reddish brown.

 
12:08 PM

Thursday 24 April: Improvisation

Today we're continuing with more soil coring. I'll post some photos of
this tomorrow.

I thought I'd post today about improvisation. Working in a remote
place often involves some improvisation. There have been many ways
we've improvised on this trip, and here's one. Normally, we like to
dry samples in nice ovens, or better yet in freeze dryers. For samples
that had to be dried here, I "built" this cute little oven. It
consists of a box with a hole cut in the bottom to go over a light.
With the help of a tripod and an extra bed, the box was stable for an
overnight drying session. And as you can see from the lower reading,
it hit my target range of 35-40°C nearly perfectly.

Warning: be careful with heat. I checked the temperature around the
light bulb quite a few times to be sure I wasn't a fire hazard. John
reports that an older tactic was to use a candle as a heat source, and
he caught his plant samples on fire once!

 
12:04 PM