map question for Pine Bend Brook Trail

[forestgnome]

On my new AMC map, which shows the same thing as my old one, the Pine Bend Brook Trail starts from the Kancamagus well away from the Pine Bend Brook, but the trail tightly follows a brook from the beginning.

From bushwacking around the area it seems that the brook along the trail is indeed the PB brook, and that the map is wrong.

Comments?

happy trails

 

[psmart]

Like the latest WODC map, the AMC maps use recent GPS surveys for all the trails, so these tend to be pretty accurate. However, both maps rely on the latest USGS quads for other features (such as streams), and these features are sometimes inaccurate.

For example, the AMC and USGS maps don't show the principal outlet from the south end of Flat Mtn Pond. This is an error that was apparently copied from the latest 7.5-minute quads, which are sometimes less accurate than their 15-minute predecessors.

There is a similar stream error in the vicinity of Paugus Mill. The more carefully you look, the more you'll find.

Some consideration was given to doing a GPS survey of certain streams for the WODC map, but it's much harder to walk along the center of a stream than a trail! So manual corrections were made to deal with the most significant problems.

 

[sardog1]

One way to know that you're competent in navigation is when you can confidently curse the mapmakers. (No offense intended to "any individual" here who might have had a hand in that excellent new WODC map! )

 

[--M.]

The Map Adventures "White Mountains Trail Map" (2nd ed.; I hear there's a new one out) shows three branches in that drainage. It's got the Pine Bend Brook Trail crossing an unnamed branch soon after leaving the Kanc, at about the 450-meter elevation. This branch drains the col to the NNE of The Fool Killer and joins the main branch just south of the Kanc, but well away from the trailhead.

The middle branch is the one labeled "Pine Bend Brook," crosses the trail at approximately the 550-meter elevation, and drains the col between North Tripyramid and The Fool Killer.

The western-most branch is called Horne Brook, and the trail runs along it for a while at what looks like the 700-meter elevation for perhaps nearly a hundred meters of elevation. It joins the Pine Bend Brook (main stem) downstream at approximately 475 meters elevation.

So the trail crosses all three branches once each.

But I don't see it "tightly following" a brook right from the start..., on this map. Is that what the new AMC map shows?

Where's Brad Washburn when you need him (RIP!)?

 

[RoySwkr]

I have never been sure which of the branches is the true Pine Bend Brook, for one thing the one labelled on the USGS map is not the same one as has the sign on Rte.112. I wrote to the FS about this but never got an answer.

 

[forestgnome]

Well, I think the mistake is the placement of the trail, and the placement of the forest road to the east, on the map. The positions of the Horne Brook and the PBB look true, based on lots of exploring in the area. A few times I've explored the Horne Brook and the ridges on either side, as well as the swampy area on the other side of the Kancamagus. Those features all seem true. Since the map shows no brook at all tight to the trail, and the fr about .3 of a mile away, I think it's the trail and fr placement that is wrong. In reality, the brook, trail and fr are within about 100' of each other.

Thanks, all.

happy trails

 

[psmart]

I'm willing to bet that the trail is correct, based on the agreement of three independent GPS surveys by the USFS, AMC, and WODC.

However, all three maps rely on the same USGS data for streams, and the AMC and WODC have copied most of the USFS road data as-is. So a single error in streams or roads would appear on all three maps.

Guess it's time for some field checks!

 

[sardog1]

Well, I think the mistake is the placement of the trail, and the placement of the forest road to the east, on the map. The positions of the Horne Brook and the PBB look true, based on lots of exploring in the area.

Yup. Found that out the time I skied that forest road a couple winters ago. It was liberating once I got past the cursing stage.

 

[RoySwkr]

It's easier to see on the USGS map because it has more detail than the AMC map, but near the road the trail follows a gully which doesn't have a blue stream but actually does contain water, I think this is the stream marked as Pine Bend Brook at the road. Similarly, higher up the trail follows another blue-less stream and actually crosses it twice although the USGS clearly shows the trail on the E side of the gully and the AMC is ambivalent.

There are 22 or 24 brook crossings on PBB Tr by various counts, it's hard to show them precisely on a map.