Question:
How
is elevation calculated?
Name: Shawana,
Mr. Bledsoe's 8th grade science class
School: Marlin Jr. High,
Marlin, Texas
Response:
Until
recently, elevation was measured using either a barometer or an
altimeter. The barometer converts atmospheric pressure into elevation.
The relationship is linear, so thinner the atmosphere, the higher
the elevation. The altimeter first calculates the time it takes
for the signal to leave the instrument, travel to the ground,
and return to the instrument (a plane, for example). This time
is multiplied by the speed of sound in the air to get the total
distance that the signal traveled. We then divide the total distance
in half to get the distance to the ground. With the invention
of satellites, however, you can use a GPS (Global Positioning
System) receiver that calculates your position based on signals
sent from several satellites orbiting Earth. This system also
has the advantage of giving a highly accurate position in longitude
and latitude in addition to elevation. Most planes, ships, boats,
and even many cars now carry GPS receivers. To measure bathymetry,
or the depth of the surface below sea level, we use the same process
as the altimeter, but we use sonar signals instead of radio waves
(which don't travel as well in water).
Question: Are you on or near
an abyssal plain?
Name: Ms. Ann Linsley's
class
School: Houston, Texas
Response:
We
actually are on a plateau, but there is an abyssal plain to the
east of this plateau off its margin. An abyssal plain is
a flat region of the deep ocean floor, usually at the base of
a continental rise. It is formed by the deposition of turbidity-current
and pelagic sediments that obscure the pre-existing topography.
Question: Do the core samples show fault lines?
Name: Ms. Ann Linsley's
class
School: Houston, Texas
Response:
We
do not anticipate any fault lines showing in these core samples
because we believe this is a very stable area with no signs of
tectonic activity. If we were in an tectonically active area,
fault lines could be seen in the core sample.
Question: What is the size
of the core samples?
Name: Ms. Ann Linsley's
class
School: Houston, Texas
Response:
A
core sample is 9.5 meters long when it comes on to the floor.
On the deck this is cut into 1.5 meter sections, capped, and labeled.
It is cut simply for the ease of handling. After some tests
are run, the core is sliced in half lengthwise, leaving a "working
half" from which samples may be taken and materials disturbed.
The other half is the "archive half" which can have
only non-disturbing tests run on it.
