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.