Lamont Doherty Observatory
Every year the Lamont – Doherty Earth
Observatory holds an open house in which
scientists share their studies and
really let the public see what and how they
do what they do. Scientists at
this research center are working together
studying different fields of the
Geologic sciences ranging from Oceanography,
Geochemistry, Seismology,
and even Marine Biology share their findings with the
public. This year like
every other year, they set up deferent exhibits and share
the current
research, studies and illustrations of the different Geologic
processes along
with their findings with anybody who is interested. For this
assignment, we
were asked to describe five of the exhibits from the LDEO open
house. The
five exhibits that called my attention the most were the
Seismology,
Geochemistry, Oceanography, Demonstration of Hard and Soft
behavior of the
surface of our, and the "Water Current Exhibit". 1-
Seismology in simple
terms is the study of earthquakes; it involves
observations of natural ground
vibrations and artificial vibrations. In this
exhibit, the scientists were
explaining how and earthquake forms and how it
can be detected even hundreds of
miles away via a Seismograph. Someone asked
the question what is an earthquake.
And the response was "well, it’s a
trembling or shaking of the ground causes
by a sudden release of energy,
energy that is stored in the rocks beneath the
surface". I thought that was
great so then, I asked how is this energy stored?
And his explanation was
very well illustrated by a simple demonstration. There
sere two bricks joined
together by a rubber band, at the end of the first brick
there was a nylon
thread which was being pulled slowly. He said imagine these
two bricks are
two plates floating on the mantle, as one moves slowly, it is"pulling" the
rubber band that is attached to the other brick and tension is
building over
time then very sudden and quickly the rubber band pulls the brick
behind it,
and this is how the energy builds up and then it is released
quickly.
(Drawing of bricks) Then he had a Seismograph, a device that
measures seismic
waves on a table and he was explaining how to read the
intensity of the
vibrations. He had first one kid jumping in front of he
seismograph, then two,
then three, then four and so one and one could see the
intensity of the
vibrations being recorded by the seismograph. He also talked
about the use of
seismic stations all over to monitors earthquakes and
artificial vibrations like
explosions, etc. The Seismology department at LDEO
monitors seismic activity in
the Northeast region of the US; here is a map of
the location of those
seismographic stations. 2- Geochemistry is the
applications of chemical
principles and techniques to geologic studies to
help us understand how chemical
elements are distributed in the crust mantle
and core of the earth. Geologists
have many ways of gathering data for this
kind of study, one of them is of
course by taking samples and analyzing them,
but in one of the labs at LDEO I
saw something I thought was very
interesting. Scientists want to know how a
mineral of a given chemical
composition behaves under extreme heat and pressure
such as those found deep
within the earth, but because they can not drill that
deep to take samples,
they came up with the idea of building a press that could
replicate specific
pressures and temperatures pretty much like those found deep
within the
earth. The press is relatively simple; it uses hydraulic power to
generate
the pressure and a special heater to generate tremendous amounts of
heat, as
much as 3000 degrees centigrade. This press uses anvels that press the
sample
from eight different directions thus increasing and redirecting the
pressure
exherted by the hydraulic press. By heating and pressuring the samples,
they
are able to study the chemical and crystal structure of different
samples.
The demonstration he gave was with a brass ball which he put
inside the press,
put the amvels on top and then pressured it just for a
brief moment and the
result was a ball with eight flat surfaces. I thought
this was so interesting
that I had to have the brass ball. 3- Deep Sea Sample
Repository. The LDEO has
an archive of sediment and rock from the beneath the
ocean floor. This material
is used for studies in oceanography, and marine
geology. Most of the core
samples are from the Atlantic Ocean, and during the
open house, scientists took
the time to show us how they collect the samples
and how they store them. The
only ways to get core samples from the Ocean
floor is by going on a ship and
physically drill the ocean floor and collect
the samples. Deep-sea cores are
long cylinders of sediment taken from beneath
the ocean floor, they contain
microscopic fossils of marine animals, volcanic
glass, sands originally from
land (terrigenous sediments), cosmic material,
and other unusual materials only
found in a marine environment which are very
sensitive to temperature changes
and chemical changes in the environment and
are therefore used as environmental
indicators for research; Volcanic glass
is an important time marker and records
geological events. Sands can indicate
oceanic currents, etc. The deep-sea
samples hold a permanent record of
magnetic history letting us know about the
magnetic orientation of the poles
as we studied in class. At the Repository
scientists showed us how they drill
and I was able to see and touch the actual
drill bits that they use to drill
the Ocean floor. In addition, we were taken to
four cold rooms were they
store the core samples, they were very big and very
cold, the reason the
samples are kept in a cold environment is to prevent
dryness and decay from
bacteria. Here is a map with all the locations were cores
have been taken for
research, notice the high concentration of locations found
in the Atlantic
Ocean. (Map of locations) 4- "Hard and Soft Surface". The
fourth exhibit that
called my attention was the demonstration of the sometimes
hard and sometimes
plastic "soft" surface of our planet. As we studied in
class, the surface of
the earth is hard and plates move through it over time,
this is the basic
principle of the Plate Tectonics Theory. In order for movement
of the plates
to occur there has to be an underlying plastic "soft" layer
(asthenosphere)
that allows the plates to move through it over time. In this
exhibit the
scientist took a very simple approach to illustrate this. He took
a bathtub, two
hundred pounds of cornstarch and mixed them together to form
this plastic hard
and yet soft solution that resembles the surface of our
planet. I never thought
this solution was so hard, it feels just like plastic
and if you try to break
it, it breaks and it feels brittle. I hit it, touched
it and I asked the person
if one could stand on it and he said of course, its
so hard that it can hold
your weight, but if you apply force slowly and
gradually, just like the stress
affects the rocks you can sink and move
through it. This is a great experiment
to try and he even gave out sheets
with the recipe on how to make this solution
at home. This was a lot of fun
especially for the kids. 5- "Water Currents".
The fifth exhibit that I
was interested in was the water convection model.
Moreover, how it
illustrates ocean currents. This was a very simple model, it
consisted of a
fish tank, a light bulb as a source of heat, a block of ice as a
source of
cold, and some kind of die to show the water moving. The tank was
about half
way full, the light bulb was at one side of the tank pointing down at
the
water, the ice was at the opposite side floating in the water, and the
die
was in the middle of the tank in the bottom. I could really see the ink
moving
to the hot spot and then rising again as it became less dense and then
sinking
again as it cooled and became more dense. This I think was a very
realistic and
vivid illustration of what really happens the oceans of our
planet. As we saw in
class, ocean currents are responsible for many
geological structures and erosion
and this model can help us how some
currents form and how they affect the ocean
floor in terms of the
transportation of sediments, etc. (Drawing of tank) In
conclusion, this was a
very positive experience that gave a broader
understanding of geology and
helped me with the terms and ideas that we discuss
in class. This really
helps to visualize some of the concepts like earthquakes,
the surface of the
earth, and the ocean currents. Thank you for giving me the
opportunity to
better understand the planet I live
in.