Welcome back earth scientists so welcome to your lab 7 introduction video for
topographic maps and contour lines so
I'm gonna warn you this is a long lab as
10 pages and there's a lot of
information but once you work through it
it really creates a foundation for
everything else that will be continuing
through this semester this is also the
last lab before the midterm goes live so
make sure that we work through this
diligently and that you make sure you
cover all your context so there's a lot
of supplementary videos that have been
posted to canvas as I know this is a lot
of information some of you may have
experiences with topographic maps and
this lab will be quite easy some people
may not so make sure you utilize all of
those resources I've shared on canvas
that being said if you find additional
resources that you think were helpful
please let me know and I'll be glad to
share them to the rest of the class so
the beginning of this lab is really
reintroducing the idea of topographic
maps and contour lines so we begin first
off with revisiting latitude and
longitude learning that the globe is
broken up in a grid system of lines and
meridians so we find that latitude our
circles that are drawn around the globe
latitude goes north to south but the
lines are drawn going all the way around
longitude our meridians are half of
great circles they intersect at the
North all the way down to the South Pole
so this content allows you to understand
more of that so go ahead and make sure
you read through that easily answer
those first couple questions once you do
that page two allows you to practice
looking at latitude and longitude so as
an example where my mouse is pointed now
if I asked you what the coordinates of
that would be the answer would be 30
degrees south and 120 degrees east so
you'll learn how to utilize a very
simplistic grid system as we move
forward we'll also introduce the public
land survey which is another grid system
of the earth house again there's videos
on canvas to help you with this make
sure you read through the content but
the idea is that most property was David
up into 40 acre parcels which is this
little box right here so the way that we
would do this is kind of like when
people ask where you live you go well I
live in Valverde all the where's
Valverde well Valverde is part of the
larger unincorporated Los Angeles well
where's that you go well on corporate
Los Angeles is north Los Angeles which
is then part of Southern California so
you kind of work your way through this
whole sequence so you start from 40
acres and you work your way up to a box
that measures 36 square miles so it's
kind of interesting and how that's
broken down who is credited with this
system I know this number is wrong I'm
sorry but it's actually Thomas Jefferson
he's the one who created the public land
survey so you'll be able to work through
this I gave you an example for letter J
so you always work in the smallest
quadrant work your way out so J out of
these four is in the southwest box
Southwest then you look in the bigger
quadrant it's in the northeast quadrant
J is in box number one two three section
number four and looking at this big
Excel spreadsheet J is part of two north
and four East that's how I got those
answers there once you learn that then
we get back into drawing topographic
maps so we learn a little bit about
topographic maps and how we have contour
lines our contour lines are not
necessarily painted on the surface but
they do have a value so if I'm standing
here and you're standing on this side of
the island on that same point we are the
same elevation above the sea level
so contour lines never cross never go up
go down they remain constant moving
forward we'll learn how to use these
elevation points to make a map so I drew
the first dots for you so you'll go
ahead and trace those dots there make
sure you read to this there's also a
video on canvas to kind of you know
reiterate this but what we're gonna be
doing is drawing a topographic map so
what ends up happening is these are all
elevation points and our job is to
connect the points well the only problem
is we can't connect points if numbers
aren't there so we have to add numbers
so what I do first as I did for Leo
elevation number forty as I put a dot on
all the 40s Dan I said well I want to
connect this 42 that 40 how can I get
there well I can see that this is 38 39
40 must be somewhere in between so I can
draw my
moving forward where's the other 40s
that are on this map well I don't see
any but I know that 38 39 40 must be
somewhere here these numbers are too
small so my line let's go back down this
way you start to figure out
mathematically where these numbers
belong so you'll do that for 35 30 25 20
15 and 10 you'll actually learn that
this map is divvied up in half there's
one mountain here and a little one here
so I'm using my mouse right here I'm
gonna draw one of the ten contour lines
this line starts here at the 10 and
works its way all the way across like
this what that will represent is
actually if you do the second one you'll
see that they kind of parallel each
other until they get separate up in here
that's actually a river system so it
goes from tens all the way down to the
eights so you have a river that flows
this direction so you have a river that
runs here you have a big mountain range
here and a small peak up here so then
you'll learn how to make a topographic
map another thing we'll look at is
topographic profiles meaning that if
this is my map looking down if I want to
you know see what it looked like from
across what would it look like so I
think if these as layers of cake so you
just see this layer goes all the way
around so this has one then there's two
there's three three dominant layers that
wrap all the way around and there's a
just one a cupcake and then here there's
one two three four on this side so
there's one cupcake on this side but
four stacked on this side this one best
matches letter B so you'll go ahead and
match the profiles you know the
topographic maps with the profiles then
we'll learn how to make a profile
there's a video as well on canvas how to
do this here is an example here is the
topographic map you're drawing you're
going to draw from here to there and you
want to bring this information down to
here so I can see what it would look
like if you were walking across that
line again there are instructions here
and a video to help this last activity
is actually then using a topographic map
so in canvas underneath this lab there's
a link then makes you prop you know pop
up this image this is a map of Lone Pine
California where the field trips
normally
it is a JPEG so you can zoom in quite a
bit and the quality is quite good so
we'll zoom back out again but anyway
you'll be utilizing this map you see
these big boxes these numbered boxes
I'll zoom it again to show you so this
is box number 13 that's section number
13 from township and range in fact if we
should assume that again trying to think
of the easiest way to get here if you'll
notice right here on your map I can't
zoom in too far because it's distorting
it you can see this has range 36 east so
we'll see there's range is in the top
and townships along the side so anyway
nonetheless you're gonna utilize this
topographic map to solve all the
questions on this lab so here we are
you'll work through this portion again
have you this is having you look at the
collar of the map which is the perimeter
of the map looking at some of the dates
in the bottom left hand corner looking
for the townships looking for the ranges
looking for elevations well where would
you find elevations let's that's kind of
fun so we know that the closer the
contour lines are together the larger
the topography or the steep or the
mountains so there must be a mountain
here there's mountains here and a really
tall mountain here so if I you know move
my map out this way and I zoom in real
close so you can get an idea this that's
February
that's a 4800 elevation mark so I need
to find a number that's higher so
usually your highest elevations on
mountains are marked like this using a
black number of benchmark for 491 your
lowest elevations will be on a brown
line so it's a little bit longer of a
lab a little more time-consuming so make
sure you get a head start on it but
that's pretty much it once you've
completed go-ahead submit to candidacy
as a PDF and then you're prepared for
the midterm exam good luck and we'll
talk soon
