Jeremy Fisher
Physics 1010
Reflective Essay
April 8, 2015
Project Reflection
I believe my project on Flood Basalts/Impact Ideas of the Cretaceous Extinction benefited not
only myself, but readers that find the topic interesting. This project included physics and branches of
geology. Based on the fact that my major is geology made this project not only interesting to investigate,
but also fun and beneficial to my knowledge of the idea. Much of the project in my opinion was mostly
on the topic of geology, but physics
still plays a roll. In my project I state
that the velocities measured in the
crustal layer and asthenosphere layer
of the Earth is 4.5km·s-1. This velocity
is measured through seismic reflection
and is a geophysical principle. Seismic
waves are used like sonar, but used to
Figure 1
determine subsurface geologic conditions like the composition of crustal layers. This is measured by
sending an array of seismic energy waves from a fixed position and analyzing the entire wave after they
have been collected at a series of geophones (or hydrophones if done on water). Both S and P waves can
be used in these kinds of tests, but P waves are usually used to measure depths of 100 feet or greater,
which in our case would be preferred. As you can see in Figure 1 our fixed position would be the boat
and our seismic waves would be created by a bubble explosion, then these reflected waves are collected
by multiple hydrophones strung out behind the boat (everything could be in front of the boat also).
Trying to understand how seismic waves and mapping worked was the most challenging part of
this project because I have not taken a class on seismology yet. This being a challenge did not scare me
from physics or geology though, but has increased my interest to keep learning and try to understand
the concepts of each science to overall better my own knowledge of how these kind of processes work. I
was briefly taught what seismic waves were in one of my earlier geology classes, so I had a general idea
of what velocity corresponding to basaltic rock meant and how it was most likely measured. Many of the
dates stated in the project corresponding to the Cretaceous period were measured by Potassium-Argon
dating techniques, which I have only a
very basic knowledge of also. These
dates are calculated by measuring the
rate of decay of radioactive atoms from a
parent isotope to daughter isotope. This
process is known as radiometric dating
and the formula used is in Figure 2 along
Figure 2
with definitions of each symbol.
I picked this project because I wanted to know how basalt floods were connected with the mass
extinction during Cretaceous period. Before this project I only knew about the impact theory, so just by
reading the title had interested me immediately. I read several research papers about how the Deccan
traps could possibly be a factor leading to the mass extinction, and what really caught my eye was the
radiometric dating results dated just before the Cretaceous-Tertiary boundary. After much research on
both basalt floods and the impact crater I put one and one together. It occurred to me that these two
theories could both be directly linked to the mass extinction which in fact is now an accepted theory by
many scientists! In summary, it’s believed that basalt flooding of what is known as the Deccan traps in
India today produced extremely large amounts of lava flow that let off trillions of tons of poisonous
gases that polluted the planet creating a dramatic effect on the biosphere of the Earth. Though life on
Earth at this time was already facing a challenge to stay alive, a large asteroid measuring up to 6 miles in
diameter entered Earth’s atmosphere a few million years after the eruptions had begun and added to
the devastation that was already occurring leading to a mass extinction. If this does not spark an interest
to anyone at all then I don’t know what would.
Overall, this project was educational, interesting, and worth the time it took to put together.
From what I’ve learned in physics, I can only imagine a meteor falling to Earth and as it falls, a traced
path behind the meteor starting from the vacuum of space to the point it enters our atmosphere and
burns its way through is imagined. All the physics behind it including its possible velocity and angular
momentum and other factors including Earth’s gravitational field seem to blow my mind. Physics has my
interest, but at no means has it been easy to understand.