By Liz Wiggins, Undergraduate
Research Assistant Extraordinaire
With our time on the island quickly
coming to an end, we were down to the daunting final task of taking inventory
of all the fossil corals we collected. By this point there were mountainous
piles of coral that had slowly accumulated at our temporary home, Dive
Kiribati. We decided to sort the corals depending on how pristine they looked
and took data on the species collected, length of the growth axis, and condition
of the piece. All together we ended up with a respectable grand total of 671
fossil corals. Although most will be stored here on the island for now, the
best of the best will be taken home for U/Th dating and analysis.
As part of my summer project as an
undergraduate student, I will be investigating how dissolution affects the
geochemistry and morphology of corals. While we were completing the inventory,
if any piece looked particularly altered it went into a special “Wiggins” pile
that was reserved for small and pitiful corals. Any piece that made my fellow
paleoclimatologists cringe only added to my excitement! I chose 10 fossil corals
that represented a gradient of diagenesis ranging from a nearly unaltered
sample to a calcite ridden and visibly dissolved poor excuse of a fossil coral.
These “special” Wiggins corals will
come home with us to Atlanta where they will undergo geochemical analysis and later
be placed in a device that simulates rain falling on the coral for a certain
length of time. Dubbed the “Rain Machine” this instrument is a self-filling
reservoir that slowly drips water onto a piece of coral at a constant rate, basically
creating artificial rainfall. Afterwards,
they will be reanalyzed to see exactly how the geochemistry and morphology
changed. This has important implications for paleoclimate reconstructions using
fossil corals as climate proxies, because nearly all of the corals in question will
have been dissolved in some way. Although the effects of some types of
diagenesis such as forming calcite or secondary aragonite have been thoroughly
tested, how dissolution alters the coral is not well understood. Christmas
Island has awarded me with excellent, horrible fossil corals that fit perfectly
for the job.
To relieve our boredom during the
long days of cataloging, our breaks consisted of visiting some of the local
shops for souvenirs to bring home for our friends and family. This island very
obviously doesn’t have many tourists, as most of the stores were laden with
canned goods and necessities for island life with very little in the way of
souvenirs. During one of our many stops we parked at a small community that
swarmed with small native children. They excitedly ran up to the truck and
began rubbing and even kissing (poor Diane) our comparatively pale arms while happily
chanting “white skin” in Gilbertese, the local language. Following the truck
all the way to the road, they cheerfully waved and yelled good-bye until we
were out of sight. But all hope was not lost, our local caretaker, Anami, led
us to some interesting native vendors that had very unique souvenirs to take
back with us, complete with jewelry and tasty treats all made on Kiritimati.
Sadly, this is our last night of
the expedition and all the final packing is nearing completion. Tomorrow we
will be sure to include one more post during our extended layover in Hawaii,
complete with a blurb from each of the remaining members of our team.
