How to properly read and understand the newest topo map from onX

Satellite imagery is one of the most important features a hunter can use. It provides crucial insight when scouting for quality habitat, timber cover, glassing opportunities and more. But in the mountainous West, the most important tool all hunters should be using is quite possibly the new, updated topo Basemap from onX.

Reading a topo map may not be as easy as simply looking at aerial imagery, but with this basic tutorial, you can get more from your maps and understand your landscapes like never before.

Topographic maps give the hunter more of a 3D view of their surrounding, showing elevation gains and losses, allowing the mountain hunter to locate peaks, valleys, saddles and slopes, which are all critical in finding mountain game species.

What’s new with onX topo

The newest topo map from onX has been upgraded with new hill shading, instead of a grey scale. The new hill shading allows for higher color contrast with a light green tree density overlay. Elevation labeling and contour lines are also more prominent and there is even blue and white shading to display permanent snowfields and glaciers.

How to use contour lines

The cornerstone for all topo maps is the contour line. The vicinity of contour lines to one another, indicates the elevation lost or gained on any slope aspect.

Contour lines close together represent a steep increase, or decrease, in elevation. While lines further apart represent a gentle slope and spaces with no lines indicate flat ground.

The lines work by connecting points on your map that represent the same elevation. Every fifth line in the sequence is a thicker line referred to as an index line for reference and somewhere along that line is the exact elevation.

To determine the elevation change in each contour line simply take the difference between two index lines, then divide by the number of contour lines in between.

Find shapes for more info

Contour lines will form shapes which define significant mountain, or hill,  and knowing these features and their contour shapes will significantly benefit hunters.

Some of the major features and their shapes are:

Topo map cliffs

Cliffs- Marked by extremely close contour lines, indicating a sudden drop, or rise in elevation

Topo map gulley

Valleys, Ravines and gullies- Contour lines in a U shaped pattern will indicate rounded gullies and V shaped lines will indicate sharp valleys and gullies. Both the U and V shapes will point uphill toward higher elevations.

Topo map ridge

Ridges and Spurs- Contour lines will form a pattern of Vs and Us pointing downhill.

Topo map peak

Peaks and Summits- Large circles with smaller and smaller circles within them. Peaks will be represented by the smallest inner ring, or circle.

Topo map bowl

Bowls- Contour lines will form a semi, or half circle, which rise from a low point.

Topo map saddle

Saddles- Contour lines will form an hourglass shape with rising, or higher contour lines on each side.

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