I'm a geologist.
That means I spend my time
trying to understand the Earth.
I want to tell you very briefly
about how I came to be
interested in geology,
what kinds of geologists
there are, what tools we use,
and then what are
the big questions
that you might get interested in
if you decided
to become a geologist.
Well, I think I always
knew I wanted to be
a scientist of some kind,
but the idea of spending
every day inside a laboratory
didn't appeal to me very much.
And then sometime
in high school,
I learned about geologists.
I learned that
these are scientists
who go out and work outdoors
and live all over the world,
so that's what I became.
And it's been great.
I've had the opportunity to work
all over this country
and in Mexico and South America
and in Africa and
in Europe and in Asia.
And this has led
to a deep understanding
of the history of the Earth.
And now I've come to realize
that that's just part
of the much bigger story
of everything that's
happened in the past.
It's one part of Big History.
So Earth is just fascinating,
and geologists study
all different aspects
of the Earth.
Some geologists are really
interested in processes,
like, how do volcanoes erupt
and what happens
when a glacier flows down
out of the mountains.
Other geologists,
and I'm one of them,
are really interested
in Earth history.
So how do you find out
about Earth history,
things that happened
millions of years ago
when there were no people
around to write them down?
Well, we look at rocks.
And here's a very good
piece of understanding.
Liquids and gasses
are always changing,
moving around,
but solids stay the same
for long times.
So thinking about
the natural case,
in geology we say
that atmospheres and oceans
forget, but that rocks remember.
So here's a rock, for example,
that remembers the great
impact 65 million years ago
that caused the extinction
of the dinosaurs,
or here's another rock,
all twisted and folded
and cooked up and changed,
and this rock remembers
the collision
between Italy and Europe
that caused the formation of
the mountain range of the Alps.
So how do we learn
about this history?
What tools do we use?
Well, in the field,
the tools are fairly simple,
and it almost seems like a joke,
but the hammer
is very important.
If you're going to break off
a piece of a rock
and bring it home to study,
you need a hammer.
And maybe you need
a compass to find out
what the orientations of the
structures in the rocks are.
So then you bring the rocks
back from the field to the lab,
and we have wonderful
new instruments
that we use for finding out
about rocks in details.
For example, there's
the electron microprobe.
And get this,
it will let you make
a whole series
of chemical analyses
across a single
grain of a mineral.
And there are
electron microscopes
that let you see things
that are far too small
to be seen just by looking
down an optical microscope.
And there are wonderful tools,
like mass spectrometers
that let geologists determine
the ages of ancient rocks
in millions of years.
So those are
the tools that we use.
So, using these tools, what
kinds of questions are there
that you might get interested
in, in trying to help answer?
Well, some of the
questions that interest me
have to do with plate tectonics.
Why is it that our planet
has plate tectonics
and continental drift
and, as far as we know,
none of the other planets do?
And what drives the plates?
What actually makes
those continents move around?
And what happens
when two continents collide
and push up a mountain range?
What happens when that
mountain range gets eroded?
So those are all questions
that one can answer
by looking at the rock record.
And then there
are questions also
that deal with
the history of life.
Why did life get started
on Earth and when?
And why has it been possible
for Earth to have life
and again, as far as we know,
none of the other planets do?
Well, we answer those questions
by looking at the fossils
that we find in the rocks.
And then there are
other questions
that have to do with climate.
When in the past
was it hot and dry?
When was it hot, wet?
When was it cold?
For example, did you know that
there were several times,
three times rather,
in the Earth's past
when our planet was completely
covered with ice and snow
and glaciers from the
north pole to the equator
and on to the south pole?
So questions:
Why did that happen,
and how was it ever
possible for the Earth
to get out of being completely
covered with ice and snow?
So climate questions
like that make you think
about the future of climate,
and what will it be like
on Earth later in our lifetimes
or in the lifetimes
of generations to come?
And maybe that leads
to the most important
of all of the
geological questions, which is:
How do we protect our Earth?
How do we keep it
flourishing so that it's a place
where people can
continue to live?
So that's just a small sample
of some of the big questions
that geologists are interested
in and that we try to solve
by looking at the rock record.
So maybe those
would interest you.
Maybe it's time
to start thinking
about becoming a geologist.
