Sit. Rep. #157: Topographic Terrain Features – I, Major and Rare

1- There are four main topographic terrain features to be familiar with.

  1. Hill, Hilltop, Mountain top, Peak, Summit, Prominences, Knoll
  2. Ridge, Ridge Line, Ridge Top, Mountain Ridge
  3. Saddle, Defile
  4. Valley, Canyon, Gorge, Ravine, Gully

1.1 Hilltop has several names.  It is where the land slopes downward in all directions from the immediate vicinity.

1.2 Ridge, Ridge Top, or Ridge Line is a series of high points or crests that connect a series of hilltops.  The Ridge separates 2 different watersheds.  And has the land sloping down on 2 opposing sides.

1.3 Saddle is a low point between two points of higher ground.  And the other two sides have lower ground.  You may see this as a break or dip along a ridgeline.  A saddle is commonly used as a Mountain Pass through a mountain chain.  A Defile is a very narrow saddle.

1.4 Valley is a 3 sided depression with those 3 sides uphill.  The fourth side is downhill.  The valleys are usually shaped like a “U” or a “V”.  Most of the time there is a creek or river at the bottom.  It may be a dry river or creek bed because of the lack of rain.  The valley bottom will run parallel to the two ridgelines.

Canyons, gorges, gullies, and ravines are the same on a topo map but usually have steeper sides or cliffs.  Think the Grand Canyon.

2- Here are three rare terrain features.  All three use “ticks” to distinguish them on the maps.  The ticks always point downhill. And are only on the downhill side of the contour line.  (Do not confuse with a railroad track where the ticks go through the “rails” and are shown on both sides of the rails.)

  1. Depression, Bowl
  2. Cut
  3. Fill

2.1 Depression is a low point in the ground or a sinkhole.  The depression is surrounded by higher ground on all sides.  A depression may look like a hilltop with added ticks.  Surface mines or pits show up on topo maps as depressions.

2.2 Cut is a man-made feature usually around railroad tracks and highways.  The cut is made into a hillside to provide a flat surface for the railroad or highway.  It may look like a small cliff with ticks.

2.3 Fill is also a man-made feature usually around railroads and highways.  The fill is the soil & rocks that are put into place to help make the flat surface.  A lot of the time you will find cuts & fills close to each other.

3- Mountain Pass is the navigable route through or over a mountain chain.  The route may go through a saddle, gap, col, or notch.  Or if you like the Gaelic term bealach (anglicised as “balloch”).  There may be “switchbacks” in the route to avoid obstacles or steep climbs.  The navigable route through the mountain pass may not be straight.

Q: What do you call a cute mountain?
R: Lava-able.


S: Why are mountain peaks never get colds or flu?
T: Because they wear snow-caps.

Semper Paratus,

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.