Tortoises and volcanoes on Santa Cruz Island
April 21, 2000
By Clare Williams and Erin Todd
Yesterday was truly a day we shall remember! Early
in the morning, we headed out to the Charles Darwin Research Center
in Puerto Ayora on Santa Cruz Island. The Center was created in
the 1960’s as a research and breeding center for endangered
animal species of the Galapagos Islands, including tortoises, terrestrial
and marine iguanas, and several species of birds. After the islands
were discovered by sailors and pirates in the 1600s, many animals
were killed for food. Because the giant tortoises can go without
food or water for many months, they were prized as food sources
by early sailors. The killing of tortoises for food, and the introduction
of non-native animals, such as goats, rats, dogs, and cats, have
had very dramatic effects on the indigenous (native) population
of Galapagos tortoises and lizards.
We visited the tortoise breeding and rearing center
where endangered species of tortoise are hatched and cared for
until they are about 5 years old. Only then are they old enough
to protect themselves in the wild. Did you know that tortoises
can live to be 150 years old? We were lucky enough to meet Lonesome
George, the last surviving member of the Pinto Island species of
tortoise. We were able to get close to a few of the adult tortoises
that are kept in outdoor enclosures. It was fascinating to watch
them eat and move around.
It was then up into the highland jungle of Santa
Cruz to see some of the volcanic features of the island. At our
first stop, we followed a very narrow path that took us through
some tall grasses and dense trees, making some of us wish we had
a machete to help clear the way. But what a sight at the end --
a dramatic view of a giant pit-crater over 100 meters deep. Pit
craters form when heat coming up from molten rock underground melts
and loosens the surface rocks. When that happens, the entire area
collapses inwards, leaving a huge, steep-walled hole in the ground.
The ones that we saw were very old, and many years of vegetation
had grown on their floor and walls.
Our second stop was to see
a lava tube that the owner of a rustic guava plantation had found
on his property. As he tells it, some years ago he noticed that
he was missing some horses. He started smelling a foul odor,
and decided to investigate the cause. He discovered that his
horses had fallen into a “skylight” --
a hole in the roof of a large cave -- that had been covered up
with grassy plants. The horses could not escape and had died. He
and his son decided to see how far the cave went. What they had
found was not a simple cave, but a large lava tube that ran right
under his property and all the way down to the ocean, over 30 kilometers
A lava tube is a long tunnel
whose walls are made of lava rock. It forms when the surface
of a lava flow cools, but the lava inside remains molten, so
it can continue to flow. How can this happen? Just like the Thermos
bottles or insulated cups that people use to keep their coffee
hot, the tube “insulates” the
molten rock inside. At the end of a volcanic eruption, the molten
lava flows down the hill and out the end of the tube, and the tunnel
empties. This leaves a tube-shaped cave with walls of lava. It
was pretty spooky and mysterious walking through a tube that many
years ago served as a pipe for transporting lava! The walls and
ceiling were decorated with bizarre and interesting rock formations,
and there were a few places where we walked on a bridge to cross
over huge cracks in the ground. We felt just like Indiana Jones!
It took half an hour to walk through the tube, and when we got
to the end, there was a single ladder up to a small skylight above.
It was really cool seeing the ladder illuminated out of the gloom
by the small amount of light coming through the skylight. As we
climbed out of the cave, we were shocked by how much cooler the
temperature was inside the cave than outside. This was an experience
that we won’t soon forget!
Parents of two of our students were inspired to write
limerick�s about their sons -- here they are!
From Ben Wigham's parents in Grenada:
There was a young scientist called Ben,
Who forgot how to pick up a pen.
His Mum and Dad said,
�E-mail us instead,
Or we�ll fly over and kidnap the hen!�
From Erin Todd's Dad:
There was a young man from Palm Beach,
Who found everything easily in reach.
For a time he was a debater, and later a ’Gator,
There were times he would learn, and times he would burn,
Many beers he could drink -- between times he would think.
When he went on a cruise, he had the Pollywog blues.
After hard work and a dance, he earned his Shellback pants!
Now his beard grows long, as he breaks into song
With a two handed slap, it’s back to his Rap!
The music is loud, but there's none that’s more proud
as the Rap man’s Dad, sitting back in his pad,
Watching pics of his son, his man on the run
in the bright Pacific Sun...