Registered: 07/31/08
Posts: 94
Loc: Michigan, just N of detroit
I have read a book but would like to hear from all of about how you practiced using a topo. I have always hiked well marked trails or used park supplied maps
Where should I start? do you just walk the trail and try to figure out where you are or is there some sort of method you folks used?
Topos are best in mountainous areas where you can make use of the contour lines on them to judge what is in front of you.
If the land you're on is pretty flat, a topo isn't a lot of use. You hear a lot of us talking about topos if we hike around mountainous areas. Often a topo is a bit of a combination of the topographic features (i.e. lines indicating how high up things are) and the features of a "map" too - like tree cover, trails, roads, etc.
So generally speaking, it's not magic. it's a map with elevation contours on it.
Registered: 02/26/07
Posts: 1149
Loc: Washington State, King County
In my case, the Army beat it into me pretty thoroughly. You might look for a local Orienteering club, or an outdoor type club in your area that might offer classes.
Or you could try to self-teach --- get a book from your local library (try inter-library loan if none is available locally) or buy one online, get a map of your area, go out in the woods and practice some.
Registered: 10/27/03
Posts: 820
Loc: north carolina
Like Brian, I got all the land nav stuff from the Army. Formal instruction does work, though you can pick it up on your own. There are several good, short books on using a map and compass -- just check out Amazon or your local bookstore.
I'm in michigan so its pretty flat, most of the hills here are less than 10ft so I always figured they were not much use with nothing to reference.
Well, the contour lines themselves may not be, although they will tell you any sort of little hill which can potentially be a reference. however, the other map type features on it (water, roads, trails, towns, etc. etc. ) will also be references - but in very flat stuff I don't find I need "topo" features, just a map - or, in my case usually - an air photo.
As phat says the topo part of the topo map ain't much use if its flat where you are. A GPS is especially useful in flat featureless terrain. There are "map guides" that explain what the symbols are that are used on maps, it pays to know what swamps look like etc. Jim
_________________________
These are my own opinions based on wisdom earned through many wrong decisions. Your mileage may vary.
Registered: 07/31/08
Posts: 94
Loc: Michigan, just N of detroit
I just want to a way to practice using a map, practicing the wrong way is learning bad habits that can be hard to fix later so I don't want to just wing it out there and teach my self how to do it wrong, the books don't really tell you how to practice, at least the two I have tried.
Jim I know that GPS is helpful to get back to where you started but I think its hard to set a waypoint to a new destination you can project a waypoint if you know the heading but not much shows on gps topo software, no camp sites or trails here in MI are found on garmin 1:24,000 or 1:1oo,ooo for that matter, I love my Vista HCX
bmwrider do you use Google Earth? If not go to http://earth.google.com/ Once you learn how to use it you will use it to plan all of your trips. Where ever the cursor is has its lat/long displayed on the screen, you simply write it down. Print satellite photos of where you are going and write way points on them with little crosses and number them. Pre enter which ever way points you will need first and always set one at your vehicle. I advise carrying a couple extra sets of batteries at first and leaving it on from the time you leave your vehicle so the entire route can be backtracked.
_________________________
These are my own opinions based on wisdom earned through many wrong decisions. Your mileage may vary.
Registered: 07/31/08
Posts: 94
Loc: Michigan, just N of detroit
The google earth trick,I played with it for 1.5 hrs right away, do you have to pay to see trails and campsites? I could not find a single place that I hike, I could find the lakes but but could not tell which part of the lake the trail should be on or get enough resolution to see any detail, thanks for showing me though it will be cool to upload my waypoints to see where I was. Can you see anything you would hike to on G.E. where you are Jim?
There are many different scales of topographic maps! For learning, I would get a USGS 7.5-minute map and choose an area with distinct topography - mountains are great. The 7.5-minute maps have enough detail that you can actually pick out features.
1)Get a book from the library- learn about contour lines. For example, contours "V" upstream. Ridges "V" down-ridge.
2)Take a good watch - or stop watch and get a real good feel of how far you walk in a specific time - say half an hour. You really need to have a sense of scale. I use topo maps a lot and to this day, I still get messed up when I think I have gone way farther than I have!
3) Get a simple compass and learn how to point your map the right direction. Each map has a arrow that shows magnetic north. Just line up the compass needle with this little arrow and you do not even have to worry about declination. Once it is oriented, then it is quite easy to pick out features. The biggest problem with beginners is that they have a poor idea of how big a feature has to be to show up on the map.
4) Keep the map out, in your hand and keep track of where you are at all times.
One place that I find very fun to play with a map is Joshua Tree National Park. All those funny little rock formations are a challange to identify.
Topographic maps use contour intervals that match the land relief. In flat areas you may have 5-foot contour lines. In mountains, you may have 100-foot contour lines. The larger area you cover (7.5-minute maps cover a small area whereas 15 minute maps cover a larger area) usually, the larger the contour interval. A lot of large area backpacking maps such as you get for a particular national park, have 200-foot contour intervals. At this scale it is very hard to pick out features. There just is not enough detail.
Be aware that if you have a 40-foot contour interval, a cliff or small hill may not show up if its total height is less than the interval. I have run into a lot of surprise 20-foot cliffs that have stopped me cold!
Registered: 02/23/07
Posts: 1735
Loc: California (southern)
Originally Posted By wandering_daisy
Be aware that if you have a 40-foot contour interval, a cliff or small hill may not show up if its total height is less than the interval. I have run into a lot of surprise 20-foot cliffs that have stopped me cold!
You conceivably could have a cliff nearly eight feet high with the contour interval marking the middle of the cliff. In most terrain, this is pretty rare, because the ground (and the contour lines) will gradually steepen as you approach the precipice.
This may not be the case in southwestern canyon country, where the ground contours can go from dead level to screaming vertical within five horizontal feet. I learned this the hard way.
I have used USGS 7.5-minute topos in flat areas that have 5-foot contour intervals. Be aware that much of contours are just interpolation between known elevations. In other words, you can have two points, one 50 feet the other 100 feet elevation and simply draw 10 evenly spaced contours between these data points or simply draw 2 lines, one for 50 feet and the other for 100 feet. The map with the 10 contour lines is NO MORE accurate than the one with 2. However, even though no more accurate I find the terrain easier to "see" on a map when a few more contour lines are already drawn. USGS maps sometimes use dotted contour lines. These lines are just interpolation.
Most topo maps now are computer generated based on Digital Elevation Models (DEM). DEM's are a grid, say 30 meters apart, of elevation points. Most DEMS are based on satallite data. These points are "ground truthed" by many fewer surveyed elevation points. I have used DEMS that were flown by private companies contracted by coal mines to create monthly mining maps. We used these maps to calculate our mineral royalty payments. These maps had 2-foot contours and were quite accurate too. You will not find this kind of map available to the public.
In general most USGS maps have 40-foot contour intervals for mountainous terrain, 20-foot contour intervals for low hilly terrain and 10-foot for flat areas. Then there are those odd-ball metric maps (I hate them) with 20-meter contour intervals.
There are books out there that explain how contour maps are made. I find it very informative to read these. That way you do not think the contour maps are less or more than they really are.
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