Wilderness Skills - Olympia Mountaineers

Optional Features
There are optional features available, in addition to the basic requirements that should be considered. These
extras will increase the cost of the compass, but may be worth the expenditure depending on the intended use.
1. Luminous points - enhances the use of the compass in minimum lighting conditions.
2. Offsetting mechanism - a feature that, when set, will automatically correct for declination in any given
area. The adjustment simultaneously takes care of both map and field bearing.
3. Sighting mirror - more accurate in taking bearings. Cover can be opened to extend straightedge
making map work easier. It may also be used for emergency signaling.
The following brands and models meet all the basic requirements. Some have additional features and are so
noted.
Make - Model Opt. 1 Opt. 2 Opt. 3
Silva - Explorer ̌ ̌
Silva - Polaris
Silva - Ranger ̌ ̌ ̌
Suunto - A10 Partner
Suunto - Leader ̌ ̌
Suunto - Locator ̌ ̌
Suunto - Navigator ̌ ̌ ̌
Map Interpretation
A map is nothing more than a drawing of a piece of the earth's surface, as would be seen
from an airplane, looking straight down. Being able to visualize terrain features from
contour lines is one of the most useful map reading skills that can be developed. The
map not only shows terrain, but also streams, rivers, lakes, roads, trails, and sometimes
man-made objects.
Maps are drawn to SCALE, which is usually printed at the bottom of the map. This
means that a certain distance on a map equals a certain distance in the field. A map is
said to have a LARGE scale when there is a lot of detail within a given area. A BAR
SCALE is usually printed at the bottom in three different units: miles, feet and kilometers. To find the distance
in the field, measure the distance between the two points of the map. Take this measurement and place it just
under one of the bar scales, and then read the field distance.
Thin brown (sometimes-red) lines called CONTOUR LINES represent the terrain
on a TOPOGRAPHIC map. Each line shows the height above sea level. Contour
lines never cross one another. Printed at the bottom of the map is the CONTOUR
INTERVAL, which is the difference in height (elevation) between one brown line
and the one next to it. Contour intervals are not the same on all maps. Typically,
they are 40, 80, 100 feet and sometimes as much as 250 feet, depending on the
scale of the map and the steepness of the terrain. Usually every fifth contour line
is wider, and its elevation is printed periodically along its length (see fig. 2).
Figure 2
Wilderness Skills Module Page 68 of 73
Olympia Mountaineers - Hiking, Alpine Scrambling and Basic Climbing