Land Nav

Question 1

What are the types of maps?

Answer 1

Planimetric
Topographic
Large scale USGS (United States Geological Survey)
Small scale Forest Service

Question 2

What does a Planimetric map show?

Answer 2

Flat, no terrain shape information.

Typically show arrangement of features such as roads, buildings, water, fences, vegetation, bridges, railroads.

Question 3

What does a Topographic map show?

Answer 3

Shows the Shape of the land.

Shows both natural and manmade features including mountains, valleys, plains, lakes, rivers, and vegetation, roads, boundaries, transmission lines, and major buildings and shows elevation with contour lines.

Question 4

What does a large scale USGS map show?

Answer 4

Similar to a topo map with terrain detail but larger scales cover a smaller area in more detail.

Question 5

What does a small scale Forest Service map show?

Answer 5

Smaller scale means it covers a larger area are the cost of less details.

Question 6

What map scale is the Forest Service?

Answer 6

1:126,720

Question 7

What map scale is Nat. Geo Map?

Answer 7

1:70,000

Question 8

What scale is a 7.5 minute Topo map?

Answer 8

1:24,000

Question 9

Why does distortion occur on a map?

Answer 9

Maps represent a curved surface on a flat piece of paper. Navigation usually takes place in a small area, on large scale maps where distortion is minimal and controllable

Question 10

Projection is..

Answer 10

A method to put earth’s surface on flat map

Question 11

Mercator Projection is used for

Answer 11

Used for topo maps

Major distortions

Preserves angles

Question 12

What is datum?

Answer 12

A mathematical model used to calculate the size and shape of the earth

Question 13

Which datum is based off of a single point?

Answer 13

NAD 27 (North American Datum of 1927). This is still used by forest services

Question 14

NAD83 is based off of

Answer 14

250,000 points and 600 satellite Doppler stations

Question 15

Which datum is used by the Global Positioning System?

Answer 15

World Geodetic System of 1984 (WGS 84)

Question 16

Which datums are basically the same,and the most common on maps and used by Sheriff, D.P.S., CAP Rescue Aircraft etc?

Answer 16

NAD83 and WGS84

Question 17

What is scale?

Answer 17

Ratio of map distance to ground distance in similar units

Question 18

1:24,000 means..

Answer 18

1 inch on map = 24,000 inches on the ground.

1:250,000 covers a very large area

Question 19

Graphic Mileage Scale- Map distance and ground distance are in different..

Answer 19

Different units. 7.5 min TOPO Map: 1 inch = 2,000 ft

Question 20

Contour lines are commonly spaced..

Answer 20

20ft or 40ft (20 is more detailed)

Intermediate Contour- Thin lines, elevation not shown

Index Contour- Thick lines with elevation shown

Question 21

What does a benchmark show?

Answer 21

elevation associated with ground marker i.e brass cap on ground

Question 22

What is spot elevation on a map?

Answer 22

Elevation shown randomly, not associated with a marker

Question 23

Forest Service map tidbits

Answer 23

½” = 1 mile

Range Lines- Run N and S

Township Lines- Run E and W

NO UTM coordinates

NO contour lines

Question 24

USGS 7.5min Topo Map Tidbits

Answer 24

Large Scale, detailed view

Has much more information

Adjacent map names

Has UTM, Lat Long, and Range Township

UTM numbers around edge every 1000m**

Lat and Long marked on edge every 2.5 minutes**

NOT UPDATED OFTEN- features may not exist

Purple tint will indicate revisions from aerial photographs

Question 25

Issues with map accuracy can include

Answer 25

Forest fires can create cleared areas which eventually become meadows Meadows can fill in with trees Roads are changed, closed,  moved Urban areas change frequently Occasional publication/printing errors Declination changes with time

Question 26

Anatomy of a compass

Answer 26

Baseplate Direction of travel arrow (does’t move, on baseplate) Orienting arrow- align with needle during fieldwork Magnetic needle- Aligns with earth's magnetic field Orienting lines- Align with North South on map Index line- marks the bearing you set by rotating the compass housing

Question 27

Cardinal Points on a compass

Answer 27

0 or 360*- N 90*- E 180*- S 270*- W

Question 28

True north is

Answer 28

The axis around which the earth rotates 

Question 29

Magnetic north is

Answer 29

The direction your compass needle points

Question 30

Declination is

Answer 30

Difference between true North and magnetic North West USA (AZ)- has an EAST declination. I.E. magnetic North is GREATER than true North East USA- has WEST declination so magnetic North is LESS than true North

Question 31

Symbols and abbreviations regarding north

Answer 31

Star- True North MN- Magnetic North GN- Grid North

Question 32

How do you use declination?

Answer 32

Magnetic to grid- Add declination “major to general= promotion” Grid to magnetic- subtract declination “gen to maj= demotion” Magnetic north is moving about 24 miles NW a year

Question 33

Compass techniques: boxing the needle

Answer 33

Direction of travel arrow is placed where you want to go Magnetic needle is placed in orienteering arrow

Question 34

Compass techniques: establishing a bearing

Answer 34

Use dominant eye Point direction of travel arrow in front of you to object Box needle Take reading and account for declination when transferring to map

Question 35

Compass techniques: back bearing, or a reciprocal bearing

Answer 35

Direction of where you came Same method as bearing but 180 degree difference If original reading is less than 180, add 180 If original reading is greater than 180, subtract 180 “ I am 2 miles from High Mt. on a bearing of 250 degrees” When reporting, report the bearing FROM the reference feature

Question 36

Compass techniques: measuring a map bearing

Answer 36

Line up compass on line between two objects Put direction of travel arrow in the direction of travel Line up N.S. orienting lines on the compass to N.S. lines on map Ignore magnetic needle This does not account for declination so keep that in mind

Question 37

Compass techniques: intersection

Answer 37

The location of an unknown point by successively sighting it from at least two (preferably three) known positions Your exact location must be known from each sighting This is taking sightings of an object so that then you can go to a map and find out its exact location. 

Question 38

Compass techniques: resection

Answer 38

Determining your location by sighting two known positions You must know your rough location and be able to see points on the map Modified Resection Only sighting one location and one linear feature that you are on, like a road

Question 39

How to reduce error

Answer 39

A 1 degree error over 1 mile  =  approx. 100 ft. error. (greater distance sighted,the greater potential for error Do short segments Walking around an obstruction Find an object on the bearing the other side and walk to it Send someone around and have them line up to in bearing then walk to them Count paces walking 90 degrees around it

Question 40

Map and compass common errors

Answer 40

Using your compass as the Only Source of navigation information. Double check against the terrain and other info frequently Not stopping when navigation info from map and compass and other sources doesn’t match up or seems marginal, stop and find the problem Being pulled off your bearing by terrain such as slopes or something that interests you  Leaving your bearing to explore without a marker to get back on bearing Not believing your compass when you get confused and lose confidence. Check it against someone else’s or against mapped terrain features.  Not knowing your exact starting point  Assuming you have an innate sense of direction and traveling with no map or compass  Letting navigation errors compound without correction  When working on map- having direction of travel or N.S. arrows backwards

Question 41

Terrain features that can help orient you include

Answer 41

Safety Baseline Major Feature Obvious at night Relatively close Catch Feature Feature on your route that you cross Handrail Feature along your route that you follow Attack Point Point to go to and then start micro navigation (bridge and road cross in the area) Aiming off Purposeful error to one side so you know which way to turn Check point Feature along route to check your location Funneling Features that funnel you to a point (ex. A stream and a ridgeline)

Question 42

How do you find you pace count?

Answer 42

Walk 100 meters and count your number of paces One pace is a left and right step Average is your 100 meter pace count to use for pace beads Account for weight  of pack and slope when estimating how many steps it will take

Question 43

Latitude and longitude formats.. what is used by DPS/dispatch?

Answer 43

Hemisphere degrees decimal minutes This is also used by CAMRA, as well as UTM

Question 44

Lat/long tidbits

Answer 44

Prime Meridian 0 degrees longitude Equator 0 degrees latitude Latitude Degree distance is constant Longitude Degree distance is not constant (closer together near poles)

Question 45

UTM (universal transverse mercator) tidbits

Answer 45

AZ in zones 11 and 12 (mostly 12) Has Northing and Easting  7.5 min Topo, 1:24,000 scale UTM Easting coordinates are measured relative to a central meridian (arbitrarily assigned at 500Km) UTM Northing coordinates are measured relative to the equator Incorporating GPS CAMRA uses WGS84 datum

Question 46

what is the current declination

Answer 46

Ranges from 10.33 degrees (yuma) to 8.65 degrees (apline). Phoenix is at 9.7 degrees

Question 47

What 2 Datum’s are “essentially the same”

Answer 47

NAD83 and WGS84