Geology 2007-2008 trip to
Although classified as an
active volcano, Poás volcano is not currently erupting.
The attraction here is a view right down into the steaming crater of
The main crater at
Poás volcano is really spectacular. When we first
arrived at around 11:00, the summit was completely socked in with fog
with a visibility of about 3 meters (10 feet). We could see nothing of the crater! There
was a brisk breeze, though, that blew the fog off in a couple of
minutes - first revealing only glimpses of the crater as holes in the
cloud would blow through, and then clearing up nicely!
Just a picture of me since I
couldn't be in the group shot :-)
The lake in the crater at
Poás is remarkable in that it is the most acid natural lake
observed on earth. The pH of the waters fluctuates with rainfall,
groundwater flow, and variations in volcanic gas emissions, but has
been measured to get all the way down to zero! The water
temperature also ranges from 50-90°C (120-200°F). If you
dropped a penny in a glass of that water, it would fizz like an alka
seltzer tablet and dissolve to nothing in around 20-30 minutes!
From the main crater, we
hiked to Botos Lake - a neutral pH lake in an old crater on the
volcano. The hike through the dense forest was like walking
through a living tunnel much of the time.
After our hikes
on the volcano, we stopped for Casado
(the typical Costa Rican meal of rice with black beans, a piece
of meat, a fried plantain or piece of yucca, and maybe a salad or corn
tortilla). Casado is
both delicious and nutritious. Casado meals typically cost around
$3 to $4, but can get up to $7 when one adds in something to drink and
a tip. This was our preferred meal in restaurants.
After lunch, we stopped at a
coffee plantation. Many coffee plantations offer a tour for
$10-15, but we opted for the free self-guided visit.
The coffee beans are surprisingly sweet! They have a hard center
with a few seeds surrounded by a soft, sweet, fruity flesh. We met a 17
year old local boy on a bike who worked the fields. He said that
he did not go to school - rather just picked coffee and rode his bike
with his friends. His hands were very tough and a little cut up,
suggesting he was telling the truth. It's fascinating to think of
the different kinds of lives we humans live.