Talk:Blue Knob (Pennsylvania)

The prominence of Blue Knob was listed as 1,721 ft, which is obviously wrong since the greatest prominence in Pennsylvania is Shade Mtn in Snyder county with 1440ft prominence. Source: www.peakbagger.com. http://www.peakbagger.com/list.aspx?lid=41207 —Preceding unsigned comment added by 96.231.117.187 (talk) 01:21, 22 August 2008 (UTC) [reply ]

The prominence is not wrong. Peakbagger lists Shade Mountain, which is incorrect. The highest prominence in Pennsylvania is Wills Mountain at 1,800 above the town of Hyndman. Read a topo map for yourself and you'll see that it was correct. —Preceding unsigned comment added by Calzarette (talk • contribs) 16:39, 22 August 2008 (UTC) [reply ]

No, the prominence is only 800 feet. —WWoods (talk) 19:46, 22 August 2008 (UTC) [reply ]

Maybe I'm misunderstanding prominence, I thought the definition included the vertical rise from the summit to the lowest vertical contour. In this instance of Blue Knob, from the summit to the town of Pavia directly below the mountain?? Please help here, I want to be accurate. However, Peakbagger's list although a good site, I would challenge some of its prominence listings (again to my understanding), on Pennsylvania. Please consider Wills Mountain in reference to it's stature. Thanks for any insight. unsigned comment added by Calzarette (talk • contribs) 16:39, 22 August 2008 (UTC) [reply ]

Hi, Calzarette. You're a bit off. Prominence — as a technical term — is measured from the summit down to the lowest contour that encircles that summit and no higher summit. Or equivalently, down to the lowest col on the ridgeline leading to a higher peak. The latter definition is what you use when you're trying to figure prominence from the topo map. The network of ridge lines is sort of the inverse of the network of rivers. Put your hand on the table with the fingers spread out — the fingers are the ridge lines, which connect at the back of the hand; the spaces between the fingers are the river valleys, connecting at the sea. See "topographic prominence" for a much longer explanation.

Prominence is most useful for deciding whether or not a particular peak is just an outcropping or a subpeak of a higher summit, or it deserves to be considered a hill or mountain in its own right. However the definition can be extended to all peaks — and has been. It may seem a little silly to measure the height of a mountain relative to a place which may be thousands of miles away; the advantage is that it's an objective measure, which can be determined as precisely as the available surveys allow, without the need for subjective decisions about what elevation to use for the "base" of a mountain.

For a simple example, consider Sugarloaf Knob (see map). The ridge line runs ESE over a couple of bumps and then NE up to the top of Laurel Hill. The prominence is not the distance down to the river, but the distance down to the lowest dip — which happens to be the first. The height of the peak is 2670±10 and the elevation of the key col is 2430±10, so the prominence is 240±20 feet.

Blue Knob and Wills Mountain were a lot harder, but I checked http://www.peaklist.org/ and found this map of 21 known peaks in Pennsylvania with over 1000 feet of prominence and the ridge lines connecting them. With that for a guide, I think I found the key cols, from which I computed the prominence values. I don't think this is Original Research — the maps have been published, even if those numbers haven't. I realized I might of course have made a mistake, which is why I included the locations I found.

Blue Knob didn't make the cut because the lowest dip on the ridge line is only ~800 feet below its summit elevation. Wills may have the highest prominence in the state, though I doubt it. I figured it to be 1,440±20, while Peakbagger says that Shade Mtn. has 1,460±20.

—WWoods (talk) 06:45, 23 August 2008 (UTC) [reply ]

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Last edited at 04:04, 27 September 2008 (UTC). Substituted at 09:51, 29 April 2016 (UTC)