We're at Point Lobos which is a state
reserve in the California state park
system located a little bit south of
Carmel on the central California coast.
This reserve is often called the crown
jewel of the state park system and so it
sees a lot of traffic. It is also
interesting for geologists and that's
because here in the park we actually see
the preserved remains of an uplifted
ancient submarine canyon.
Nearby here just off to the north are
two modern submarine canyons that cut
the modern slope that leads down into
the abyssal plain of the Pacific Ocean.
The largest of these is Monterey Canyon
the smaller is Carmel Canyon and these
are conduits by which sediment is moved
from the beach and from the rivers like
the Salinas River down into the deep sea.
We can't actually walk on the canyon
floor and so our understanding of it is
limited by remote sensing tools and
dredging samples and things like that
but here we can actually see what the
long-term fill of sediment of such a
canyon is like because it's been
uplifted, partially eroded back and so we
can actually walk down inside the guts
of the fill of this ancient submarine
canyon.
Submarine canyon is actually different
all over the world. Some of them on
coastlines that are relatively not
tectonically active like in the Gulf
Coast of the United States often are
filled with mud because there isn't a
lot of course debris that's available. I
feel here is very coarse composed of
coarse gravel cobbles and boulders as
well as some sand and finer things but
it's very coarse and it's coarse because
there were mountains nearby you were
eroding them down and dumping the coarse
debris down into the head of the
submarine canyon and then flushing it
out into the deep sea. There are really two
kinds of questions that we ask here. The
first is a basic science question and
that is what are the processes by which
sediment moves into submarine canyons
and comes to rest and there are features
within the geology that part that allow
us to answer some of those questions but
those can be translated over to the
second reason that we come to study
places like this and that is oil and gas
exploration. It requires really a special
set of geologic circumstances for oil and gas to accumulate. Submarine
canyons are one such environment yet
they're so far below the sea surface and
even farther below the bottom of the sea
floor that it's impossible to know what
they're actually like. That's why coming
to a place like this where you can
explicitly walk on the sediment floor 55
million years ago and understand where
the reservoir sediments are and where
they aren't this gives us an opportunity
by analogy to consider what kinds of
things may occur deep beneath the earth
in those places where we're looking for
oil and gas and by doing that we
potentially reduce some of the risk
involved in exploration in those places.
One of the wondrous things about the
National Park System and the state park
system here in the U.S. is that many of
the parks are there because of geology
and while most people come to see the
magnificent scenery or maybe the
wildlife, we geologists go to a place and
we see all of those things but we see
ancient landscapes unfold before our
eyes.
So here it's as if we're able to go in
a submersible to the bottom of the
ocean 55 million years ago and see
what's going on, see what's being
deposited. Seeing boulders falling off
the side of the submarine canyon walls.
It's just a sort of way to even more
deeply appreciate the parks that we have
here in the U.S.
It's a case of clues. It's like forensics.
We try to find features that tell us
precisely how this was moved or what was
happening how strong the current was.
These rocks, like virtually all other
sedimentary rocks, are layered. Makes
sense. Oh the stuff is on the bottom of
the pile and the youngest stuff is on
the top so there's an order to this and
so it's a little bit like a history book.
Each layer represents an event and
events stack up but sometimes between
events nothing happens so you don't get
anything deposited and it's as though in
a history book you came in and tore out
some pages and so you get a record of
what this King did and then suddenly
somebody else is doing something and
you don't know what happened in between, but
if you use your geologic record
carefully you can put together a pretty
nice history even if there are holes in
it now and then.
