Maps--can't trust them either! | High Sierra Topix  

Maps--can't trust them either!

If you've been searching for the best source of information and stimulating discussion related to Spring/Summer/Fall backpacking, hiking and camping in the Sierra Nevada...look no further!
User avatar

Maps--can't trust them either!

Postby balzaccom » Sun Sep 25, 2011 5:51 pm

These days, just about every backpacking discussion group includes people warning about the dangers of relying exclusively on GPS units for navigation. We know, because we’re often the ones who are issuing the warnings. We’re big believers in knowing where you are, and how to get where you are going without depending exclusively on any battery powered device. And a GPS unit won’t always show you the terrain you might need to cross. Coming down the face of El Capitan to get to Yosemite Valley isn’t an option for most people…even though a GPS unit shows you that it’s only a about 1/4 mile.

And it seems that every few weeks we read a news story about someone who follows their GPS blindly into increasingly primitive roads and conditions…and has to be rescued. So don’t put all your faith in your GPS.

But a couple of recent experiences have us taking a bit of the same approach to the old school standby of printed maps and compass. Because it turns out they can lead you astray as well...

We’ve noted some problems with some of the National Geographic maps. Red Can Lake in the Emigrant Wilderness is called Red Canyon Lake on their map. And another section of trail in Yosemite that was marked at 6 tenths of a mile turned out to be less than 150 yards. So maps are fallible.

How fallible?

Driving back from our trip to the Ansel Adams Wilderness, we were stuck in a massive traffic jam on Labor Day Monday on Highway 41 in the town of Coarsegold (corrected data). No worries, because we quickly pulled out two different printed maps (AAA and DeLorme) and found a series of side roads that would circumvent the problem. And we love exploring like this.

So we quickly turned off towards the town of Raymond, and followed the maps through town and towards LeGrand. The roads were nicely paved, empty, and we felt pretty darn clever about the whole thing.

Until we got to the junction that led north to Mariposa. We didn’t turn right, because that would take us miles out of our way. But the only other option was straight ahead: a primitive dirt road heading off into the wilderness. Both of our maps showed it as paved. Maybe the dirt part was only a mile or two.

Nope.

Image

For the next twelve miles or so we drove on one of the most isolated roads we have ever seen in California—miles and miles of unfenced, untouched grassland. An ocean of foothills, and not another vehicle in sight. Although we did find a sign for some property for sale…

Image

In the end, we finally came out the other side, covered in dust, and continued on our way into LeGrand and beyond. Yeah, we were delayed by the slow going on the dirt road, but not much more than if we had stayed in the traffic jam.

When we got home, we checked Google maps, which shows the route as a very primitive dirt road. So at least their maps are more accurate than the other two.

And we’re just grateful that we didn’t have to hike out of there somehow because our car broke down.

You would have heard about it on the news, of course.
Last edited by balzaccom on Mon Sep 26, 2011 7:51 pm, edited 1 time in total.
Balzaccom

check out our website: http://www.backpackthesierra.com/



User avatar
balzaccom
Topix Fanatic
 
Posts: 1288
Joined: Wed Dec 17, 2008 9:22 pm
Experience: N/A

User avatar

Re: Maps--can't trust them either!

Postby Ikan Mas » Sun Sep 25, 2011 6:45 pm

My GPS is more of a way of documenting where I have been. Its a good unit, and I will use it to confirm where I am, but wouldn't depend on it for navigation.

I too find Nat Geo maps less than stellar when it comes to accuracy, and refuse to buy them for west coast locations. The Mt. Rainier map leaves out some important trails. Unfortnately, for some places, there is little choice. I recently bought one for Utah and found it hard to understand as well. I haven't had a chance to verify its accuracty, but I am concerned.
User avatar
Ikan Mas
Topix Regular
 
Posts: 338
Joined: Tue Nov 10, 2009 9:43 pm
Experience: N/A

Re: Maps--can't trust them either!

Postby Cross Country » Sun Sep 25, 2011 8:21 pm

When GKaz and I drove to Florence Lake and back we listened to the spoken instructions. They were entertaining at times and comical at others until it sidetracked us with directions for a left turn on the way back close to H99. I knew the turn should have been right but had to make a near split second decision and I followed the voice only to be detoured and detained. Quickly I knew the correct route but not before the delay. I didn't feel confidant in going the route I had been 15 - 20 times. The problem was I just didn't feel confident to follow a 68 yo memory because I hadn't been there there in 10 -20 years. It turns out my old memory was better that the GPS voice.
Cross Country
Topix Fanatic
 
Posts: 1119
Joined: Thu Dec 24, 2009 11:16 am
Experience: N/A

User avatar

Re: Maps--can't trust them either!

Postby SSSdave » Mon Sep 26, 2011 10:40 am

Maps have always had errors that is not at all surprising considering their complexity and the ever changing infrastructure issues with roads etc. USGS topographic maps always have some errors too, especially with non land form elements.

Over decades I've driven lots of backroads mainly during spring search wildflowers and have been on that one you mentioned out of LeGrand. There are many such roads in rural California farm and ranch regions.
User avatar
SSSdave
Topix Fanatic
 
Posts: 1965
Joined: Thu Nov 17, 2005 11:18 pm
Location: Silicon Valley
Experience: N/A

User avatar

Re: Maps--can't trust them either!

Postby rlown » Mon Sep 26, 2011 11:53 am

probably should throw out all the '75 vintage AAA maps in my truck, eh? :D

If I want to get around a traffic block, I follow the tour buses on 140. They know the quick routes.
User avatar
rlown
Topix Junkie
 
Posts: 5328
Joined: Thu Oct 25, 2007 5:00 pm
Location: Petaluma and Wilton, CA
Experience: Level 4 Explorer

User avatar

Re: Maps--can't trust them either!

Postby TehipiteTom » Mon Sep 26, 2011 2:21 pm

Okay, had to look at a map, but...you mean Highway 41, not 140, right? And Coarsegold, not Rough and Ready?
User avatar
TehipiteTom
Founding Member
 
Posts: 814
Joined: Thu Aug 24, 2006 8:42 am
Experience: Level 4 Explorer

User avatar

Re: Maps--can't trust them either!

Postby balzaccom » Mon Sep 26, 2011 7:32 pm

LOL! Yes...on both counts!

We drove from Coarsegold to Raymond...and then into the abyss.

Thanks for the correction!
Balzaccom

check out our website: http://www.backpackthesierra.com/
User avatar
balzaccom
Topix Fanatic
 
Posts: 1288
Joined: Wed Dec 17, 2008 9:22 pm
Experience: N/A

User avatar

Re: Maps--can't trust them either!

Postby giantbrookie » Mon Sep 26, 2011 9:25 pm

Yes, there do tend to be a few errors on maps, particularly with cultural features instead of topography or stream locations. I recall one USFS map (no topo) that showed a nice maintained 2WD road that would have allowed me to go from the Goat Mtn. area of the northern Coast Ranges to near Clear Lake. The road went from a nice gravel road to a more primitive 2WD road and then to no road at all. After several attempts to see whether a road really existed (not successful), I had to reverse my way out east (total of 2 hours plus wasted).

There is a certain USFS wilderness topo (Sierra Nevada somewhere) shows a key road end that is about 1 mi west of the true road end. If one had GPS AND the map one could figure the true end position of the road. But since I use neither a compass or GPS for my recreational hikes, I had to quickly figure the position of this road end from topography, which wasn't easy given it was pretty heavily wooded and the line of sight limited. Fortunately my best guess was spot on and the first hike Judy and I made to a certain trailless lake off of this road end was successful.

I have encountered one fairly large error on a USGS topo (older 15', don't know if this error is on the newer 7.5') map of the Russian Wilderness which was then propagated onto the USFS Russian Wilderness/Marble Mtns topo. This is the position of Wicks Lake. The position shown on the topos is where one thinks the lake should be at the head of a cirque at the head of a valley. This position, however, is occupied by a cluster of brush (Judy and I found this out the hard way). The true position of the lake is about 500' higher on a bench on the cliffs above. Unless they've corrected this error on the 7.5' and the revised Russian Wilderness USFS topo, I'd guess Wicks Lake doesn't get visited too much. It's too bad it only has brookies to 11" in it.

I found a significant topography error in an early edition (pre USGS) topo on the Cerro Gordo area in the Inyo Mtns. east of Lone Pine. This was during my undergraduate days and I was in a geologic mapping class. It was the first day and the professor was doing the usual "tour of the field area" day and checking with us periodically to make sure we located ourselves correctly on our topo map base. At one juncture he checked all the maps and remarked that the locations looked good, then got to mine. Diplomatically he explained to me that I had mislocated the position by about a half mile. To the professor's surprise, I replied that in fact everyone else was off by 1/2 mi or more because the topo map was incorrect. After he recovered from his initial shock I pointed out that the bulk of the topographic features were inconsistent with everyone's presumed position and that it was a spurious pinnacle or a missing one (it has been 32 years so I forget exactly what the error was) that caused folks to mislocate as they had.
Since my fishing (etc.) website is still down, you can be distracted by geology stuff at: http://www.fresnostate.edu/csm/ees/facu ... ayshi.html
User avatar
giantbrookie
Founding Member & Forums Moderator
Founding Member & Forums Moderator
 
Posts: 2439
Joined: Wed Dec 28, 2005 10:22 am
Location: Fresno
Experience: N/A

User avatar

Re: Maps--can't trust them either!

Postby oldranger » Tue Sep 27, 2011 11:23 am

Since I frequently use the old 15 minute series maps I obviously can't take trail location or TH locations too seriously. Since I am not completely anachronistic I do purchase updated maps such as the Nat. Geographic Maps or Harrison Maps. Occasionally the descrepancy between the old and new maps provides a hint that there may be an alternative route preferable to the current trail. Of course many changes in trails are too small to actually show up on maps. A couple of weeks ago I followed the trail from Tilden Lake down to the PCT (TR coming this winter!) and in places I could see at least 2 differnent trail grades in addition to the current one.

As GB noted sometimes even the natural features are incorrect. The one I remember most clearly is on the old 15 minute series map that covered most of the Sugarloaf Creek/Roaring River drainage (Triple Divide Peak quad?). At any rate it showed the outlet of Lost Lake flowing from the NE corner of the lake when, in fact, the outlet was at the SE corner.

Nothing, as GB aptly demonstrated, substitutes for a good eye for the terrain.

Mike
Mike

Who can't do everything he used to and what he can do takes a hell of a lot longer!
User avatar
oldranger
Topix Junkie
 
Posts: 2164
Joined: Fri Jan 19, 2007 9:18 pm
Location: Bend, Oregon
Experience: N/A

User avatar

Re: Maps--can't trust them either!

Postby East Side Hiker » Thu Oct 13, 2011 1:51 pm

Right on Balzaccom! You are so right. La Grande, at least, has a good saloon.
User avatar
East Side Hiker
Topix Regular
 
Posts: 391
Joined: Tue Oct 19, 2010 8:10 am
Experience: N/A

User avatar

Re: Maps--can't trust them either!

Postby dave54 » Sat Oct 15, 2011 9:50 pm

Untrustworthiness (is that a word??) exists everywhere.

I know of one Forest Service K-tag, posted by a licensed surveyor, off by 6 miles. It shows R. 7E when it is R. 6E. A typo error rather than a surveying error, but still enough to seriously confuse someone relying upon the tag for navigation.

OTOH -- I enjoy the old 15 minute topo quads (and 1950's vintage National Forest visitor maps I have). I like looking for old trails on the map that no longer exist on the ground and try to follow them.
=~=~=~=~=~=~=~=~
Log off and get outdoors!
~=~=~=~=~=~=~=~=
User avatar
dave54
Founding Member
 
Posts: 774
Joined: Fri Oct 28, 2005 10:24 pm
Location: where the Sierras, Cascades, and Great Basin meet.
Experience: N/A

User avatar

Re: Maps--can't trust them either!

Postby East Side Hiker » Sun Oct 16, 2011 1:48 am

Maps cannot replace on the ground experience.
User avatar
East Side Hiker
Topix Regular
 
Posts: 391
Joined: Tue Oct 19, 2010 8:10 am
Experience: N/A

Next

Return to Backpacking / Hiking / Camping



Who is online

Users browsing this forum: Broot, Google [Bot], Yahoo [Bot] and 5 guests