MAP SKILLS FOR ENVIRONMENTAL SCIENCE - McMaster University

MAP SKILLS FOR ENVIRONMENTAL SCIENCE
Gord Beck | Cathy Moulder | Lloyd Reeds Map Collection, Mills Library
Env. Sci. 1G03

TOPOGRAPHIC MAPS
Topographic map Google map
1. High level of detail
2. Produced in series
3. Elevation information

COLOURS & SYMBOLS
• International system of colours & symbols
• intuitive
Image from: Natural Resources Canada, Topographic Maps: the basics
Blue = ?
Green = ?
Brown = ?
Pink = ?
Black = ?
Legend
found on
back of map

MARGINAL INFORMATION
• Index to adjoining map
sheets
• Coordinate systems
• Publication date
• Information currency date
• North arrow
• Magnetic declination
statement
• Scale
• Contour interval statement

SCALE:
(1) GRAPHIC LINE OR BAR SCALE
2 cm on the map = 1 km in the real world
1 cm on the map = .5 km in the real world

SCALE:
(2) VERBAL

SCALE:
(3) REPRESENTATIVE FRACTION
1:50,000 = __1___
50,000
1:10,000 = ___1___
10,000

SPOT HEIGHTS & CONTOURS
Spot Heights to Contour Lines

CONTOUR LINES
Image from: Natural Resources Canada, Topographic Maps: the basics

STREAM GRADIENT
RISE
Difference
In elevation
(metres)
Point A:
250m asl
10m
RUN
Horizontal “real world” distance (metres)
GRADIENT: RISE = Vertical Distance (10m)
RUN Horizontal Distance (1000m)
10m = 0.01 (no units)
1000m
1000m (1km)
Point B:
240m asl
Section 8.12 in the Handbook for the Earth & Environmental Science Student

STREAM GRADIENT
1. Use your coordinates to locate
your start and end points.
2. Use the first contour line you
come to as the elevation for
each point and calculate the
difference in their elevations.
3. Calculate the “real world”
distance between them using a
ruler and the map scale.
GRADIENT = RISE = VERTICAL DISTANCE
RUN HORIZONTAL DISTANCE

CROSS SECTIONAL PROFILES
Use contour lines to create a cross section of the land surface
STEP 1
2cm = 1km therefore 12cm = 6km
Use coordinates to find your start and end points
Determine “real world” distance between points by using map scale
Section 8.4 in the Handbook for the Earth & Environmental Science Student

CROSS SECTIONAL PROFILES
• Place the edge of a piece of paper along the line.
• Mark off the distance between both points based on
the map scale determined in STEP 1
• Mark all the contour lines and record their elevations.
• Mark all features like streams, roads, etc.

STEP 3: Create a Graph
180
160
140
1cm
120
100
80
metres
Y = Elevation (m asl)
X = Distance from A to A’ (“real world” m or km)
100
120
• Align your paper strip with
the bottom (“X” axis) of
your graph and transfer
your contour, scale and
feature data.
• Assign your own scale to
the Y axis (e.g. 1cm=20m).
120
100
80
stream
scale
80
100
120
140
160

STEP 4
180
160
140
120
100
80
metres
100
120
120
Plot the corresponding elevation at each point
100
80
scale
Connect the dots and you’ve got a cross sectional profile!
stream
80
100
120
140
160

STEP 5
180
160
140
1cm
120
100
80
metres
Calculate the Vertical Exaggeration (VE)
1:2,000
1 cm on the graph = 20m or 2,000 cm in the real world
Vertical scale
2cm
1:50,000
1 cm on the graph and map = .5 km or 50,000 cm in the real world
Horizontal scale

VERTICAL EXAGGERATION
VE =
Vertical scale
Horizontal scale
=
__1__
2,000
__1__
50,000
.0005
= = 25
.00002

MAP REFERENCING SYSTEMS
Latitude & Longitude
(Spherical system)
Universal Transverse Mercator
(Grid system)
Military
(Grid system)
All systems use the intersection
of an X and Y plane
These 3 systems
appear on Canadian
topographic maps

UTM GRID SYSTEM
Universal Transverse Mercator (UTM) Grid
is a “planar” coordinate system.
It deliberately attempts to remove
the curvature of the earth in order to
work on a flat surface.
To create the flat surface
the Earth is divided into 60 strips
like sections of an orange.

When recording a UTM coordinate:
the Easting is always written first
the Northing is always written second.
Read:
Right...
(Easting first)
...Up
(Northing second)

Step 1: Identify the UTM Grid
It appears as
BLUE lines
on the surface of the
map, and is indicated by
BLUE numbers
outside the neat line.

Step 2: Easting
Read the Easting value for
this line at the top or bottom
edge of the map.
Your first 2 digits are: 18
Locate the blue line which is to the left (west)
of your target location (an airport in this example).

Your 3 rd digit is a: 6
Hint
The Map Collection has
special scale rulers for
this purpose, but you
can also use any ruler
graduated in millimetres.
• Use a ruler or “roamer” to measure the distance
of your target location beyond the Easting line.

Add this digit to your Easting.
186

Step 3: Northing
Read the northing
value for this line at the
left or right edge of the
map.
Your next 2 digits are:
47
Locate the blue line that is below (south)
of your target location.

Your 6 th digit
is a: 5
• Use your ruler or “roamer” to measure the distance of
your target location above the Northing line.

Add this digit to your Northing.
475

Easting: 186
Northing: 475
6-digit: 186475
Combine the Easting & Northing numbers
to form one 6-digit coordinate.

LATITUDE & LONGITUDE
• There are two base lines or zero lines for the Latitude &
Longitude coordinate system.
• The base line for Longitude is called the Prime Meridian
• The base line of Latitude is the Equator.

LATITUDE & LONGITUDE
• When you calculate a coordinate you are actually
establishing the angle at which your point of reference
is located in relation to the zero line.
• For this reason the units of measurement are angular
and shown in Degrees, Minutes and Seconds.

LATITUDE & LONGITUDE
50 degrees, 20 minutes and 10 seconds = 50˚ 20' 10''
• A circle = 360 degrees
• 1 degree = 60 minutes
• 1 minute = 60 seconds
A Degree is designated by a superscript “o”
A Minute is designated by a single prime mark '
A Second is designated by a double prime mark "

LATITUDE & LONGITUDE
• Your coordinate should always include the ordinal
(compass) direction
For example: 50˚ 20' 10'' N
Latitude 50˚ 20′ 10″ N,
Longitude 105˚ 33′ 30″ W
is Moose Jaw Airport!
…and, of course you need a pair of coordinates to
uniquely identify your location.

LATITUDE & LONGITUDE
Step 1:
Locate the Referencing System on the Map.
It appears at the neat line of
the map, and is indicated by:
BLACK numbers
and
BLACK & WHITE bars.
Disregard all BLUE lines and
BLUE numbers. They are not
related to latitude & longitude.

LATITUDE & LONGITUDE
Step 2:
In Which Direction Should You Count?
In this example, the top of the map displays the larger number.
Remember that you are measuring
away from the base zero line, and
towards the larger coordinate
number.
So you are measuring North on this
side of the map.
Latitude ˚ ′ ″ N

LATITUDE & LONGITUDE
Step 3: Degrees
On a 1:50,000 scale map
the degrees usually do not
require calculation…
…as the area depicted
on the map is smaller than
one degree of latitude.
Latitude 50˚ ′ ″ N

LATITUDE & LONGITUDE
Step 4: Minutes
Each black unit = 1 minute
Each white unit = 1 minute
Canadian topographic maps at 1:50,000 scale show minutes by
means of these black and white markings along the neat line.

LATITUDE & LONGITUDE
the target is farther than 18,
but not as far as 19 minutes
Count to the last full minute
mark before your target and
record that number as your
minutes.
Latitude 50˚ 18′ ″ N

LATITUDE & LONGITUDE
Step 5: Seconds
30''
Latitude 50˚ 18' 30'' N
There are 60 seconds in a
minute so the trick here is
dividing this small length into
sixtieths.
Count up the seconds until you
are even with your target.
In this example we are at the
half-way point so the answer is
30 seconds

LATITUDE & LONGITUDE
So now you have your “X” plane coordinate:
Latitude: 50˚ 18' 30'' N
Repeat the same process to get your “Y” plane coordinate:
Longitude: ___ ___ ___ W
“Y”
“X”
http://www.portcities.org.uk/london/server/show/conMediaFile.6132/Latitude-and-longitude.html

NORTH ARROWS
On topographic maps, direction is indicated in 3 ways:
True North (TN)
geometric/physical north pole
Magnetic North (MN)
location a compass points to,
changes annually at a constant rate
Grid North (GN)
North orientation of the UTM Grid
Sections 8.7 and 8.8 in the Handbook for the Earth & Environmental Science Student

MAGNETIC DECLINATION
Describes the movement of
Magnetic North (MN)
away from
True North (TN)
It is the measurement of the angle shown as “X”
It is expressed in degrees and minutes
Annual rate of change found below the arrows
(in this example: 4.3' per year)

MAGNETIC DECLINATION
Find magnetic declination for 1993 (angle MN TN)
9°39' - 0°31' = 9°08'
Determine total change
Years passed: 2010 – 1993 = 17
17 * 0°4.3' = 73.1' 1°13.1'
Add change to 1993 declination
9°08' + 1°13.1' = 10°21.1'
Therefore: the magnetic declination
for 2010 would be 10°21.1'

HOURS
Monday to Thursday: 9 a.m. to 9 p.m.
Friday: 9 a.m. to 5 p.m.
Saturday & Sunday: CLOSED