Kayak Lake Mead's Map & Compass
These brown squiggly lines connect equal points of elevation, thus contour lines portray not only the elevation but the shape of the land. The intervals of the lines vary from map to map, but on a USGS 1:24000 map the interval is usually 20’, 40’, or 10 m (32.8’), with every 5th line bold. Thus, on a map with a contour interval of 40’; the difference in elevation between any two lines is 40’ and between any two bold lines is 200’. The closer the lines are the steeper the terrain is.
1. If I was running from WP 2/4 over to WP 3; I would run the blue line, “contouring” around the hill and around the gully, rather than measure a bearing and run straight over. If is about 20% further, but avoids going straight up a steep hill, it avoids side sloping (walking at right angles to a steep slope), and it avoids losing about 50’ of elevation in the gully which must be re-gained going up to WP 3. Certainly this is only a short distance (about 0.67 km straight line) but, (1) if I’m there to run I want to run and not deal with the steeper slopes of hill and gully and the rockier terrain that would be included and (2) it has been estimated
that one step uphill requires 8 times the energy of one step on flat terrain and so on a longer distance this is going to add up fast.
2. In running from WP 2 to WP 3; again I would run the blue line. If you go the blue line it is about 3 times further than running straight across the gully, but it avoids a 100 m loss in elevation; 32 stories down and 32 stories back up again. Once again my choice is to “contour” around the gully.
NOTE: Contouring around an obstacle is not
always the best choice; not if you are going to
encounter worse terrain than you’re avoiding,
not if what you’re avoiding is easy going
terrain, and not if the route around is way too
far out of the way.
ALSO: Often you can go up to 2 times out of your way on road or trail and still make better time than if you had gone overland on rougher terrain.