Geographical Features


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Geographical Features (Canyons)

Here I'm using a short hike up a seasonal stream bed that I recorded a track in while in search of a geocache. It gives you an example of what you can expect from the different mapping products in regards to Moderate geographical features.

To begin with, we have what most Americans view as the basic hiking navigation aide. The 1:24,000 scale (1:25,000 scale in areas) USGS topo, often referred to as the Quad.

A quick glance at the 1:24,000 scale map by someone experienced in using TOPO's shows the journey going up a streambed, in a canyon on a fairly steep hillside. Based on what I see on the map, I would expect the canyon walls to be fairly steep, and somewhere in the region of 100 to 200 feet feet deep. You can also make out twists, turns, and assorted features that would make pinpointing your position within the canyon fairly easy. You can also tell there are powerlines and view a source of water at a spring.

The Garmin TOPO is based on a less detailed 1:100,000 scale USGS TOPO map. The map doesn't show the streambed, but you can still tell it's a canyon, fairly steep, maybe a little over 150 feet deep. Twists, turns, and distinctive features are harder to identify with this map than with the more detailed 1:24k product, but I could still probably successfully navigate with this map and a compass. The map also shows the power line, and has the spring shown as a POI. You can also see the Forest service boundaries on this map. While not as detailed as you would want for route planning, it's probably not a bad compromise for use on the very limited GPS display.

Looking at the MapSend TOPO, you have no idea there is a streambed here, nor can you tell there is a canyon. Looking at the map, it appears more like a steep slope up a featureless hill. The averaging of terrain features is so severe that it's pretty difficult if not impossible to pick out geographical features to help you navigate with on this sort of TOPO map. About all it helps with is letting you know you're going to be heading up. You also don't get the added navigational advantage of knowing where the powerlines are, but the spring is included as POI data.

As you can see, for the most part you'll want a 1:24,000 scale map if navigating by foot in this sort of terrain. The 1:100,000 scale Garmin TOPO is useable though. Magellans TOPO averages out the terrain features to the point where it's pretty much only useful to determine elevation change between point A and B. It's not of great use for route planning, or using to navigate without the GPS.