Simply put geology is the science that
pursues an understanding of planet Earth.
And specifically in this course, Physical
Geology, we'll learn how materials such as
rocks and minerals form and how we
classify them. We'll also learn how the
processes that are operating on the
planet help to shape it and produce the
unique landforms that we see today like
The Devil's Backbone behind me.
The first interests and murmurings about
trying to understand Earth processes
date back to the early Greeks who
observed fossil fish in rocks and
wondered about them more than 2,300
years ago. For many many years the earth
surface was thought to have been the
product of supernatural and
catastrophic processes.  In the
eighteenth-century a Scotsman by the
name of James Hutton, who is often
regarded as the father of modern geology,
made some compelling observations in
his corner of the world. James Hutton who
was a farmer, physician, and geologist,
among other things, was a great observer
of nature. He realized that geologic
features such as mountains are not
permanent features rather they have been
shaped by the agents of erosion. In
addition, he realized that the great
thicknesses of sedimentary rock we find
on the continents are the products of
that erosion, a slow movement of sediment
removed from the land and deposited into
oceans.
This means that the earth's surface is
always changing,
it's never the same. To be sure these
were rather bold ideas for the time.
Ideas that assumed a very very old earth
that was shaped by processes operating
on its surface. This idea, known as
uniformitarianism, can be summed up by
the phrase the present is the key to the
past.
In other words, the processes that we see
operating on the Earth's surface today
are the same as the processes
that we saw operating on the earth
in the geologic past. Using this idea I
can observe sediments moving down a
river and I can see them deposited into
gravel and point bars. And then I can go
to a rock outcrop like this one.
Do you see that it's made up of gravels
and pebbles just like those that i saw
in the river?
This is a rock that geologists referr
to as conglomerate. It's a sedimentary
rock and I know that it was deposited in
a river a long long time ago in the
geologic past. It was deposited in that
river, the sediments were lithified, and
then later uplifted due to plate
tectonics. The present is the key to the
past. And just as James Hutton asked, "What
more can we require?" Nothing, but time. So,
join me in our exploration of the earth.
See you in class!
