Good information posted already.
A very useful list which shows the prominence of many Adirondack peaks is this
Peakbagger.com list of 3700' Adirondack peaks . The numbered peaks have 160' clean prominence. This is their standard criteria for northeastern US peaks. The difference between clean prominence and the standard col rise definitions is one contour interval. So combined with the 40' contour intervals of some White Mountain USGS maps; 160' of clean prominence is the equivalent of the standard 200' rise criteria used by the AMC and many other northeast list makers. Similarly it also covers one 10 meter (32.8') contour interval on the current metric Adirondack maps. This list also includes an isolation / distance from the parent mountain (nearest higher neighbor mountain from the perspective of prominence). On this list the 4009' Yard has a 0.9 mile distance/isolation from Big Slide and with a 203' clean prominence (based on the current metric maps).
Some historical information on why Yard is not a 46er peak. The original criteria that the Marshall brothers and Herbert Clark used to create their list of Adirondack 4000' mountains involved both elevation rise and distance: "300' rise on all sides (prominence)
or 0.75 mile distance to the nearest higher peak." Only 30 of the 46er peaks have a 300' rise/prominence on the current and also the 1895-1904 era maps used by the Marshalls and Clark. 6-8 of the 46er peaks do not even have a 200' rise/prominence (depending on which set of maps are used). Iroquois, Gray, Armstrong, Donaldson, and Emmons do not have a 200' rise on current maps nor on the USGS maps used by the Marshall brothers and Clark. Nye also does not have a 200' rise, and it is not a 4000' peak on current maps. Carson (South Dix) and Dial - had a 200' rise on the 1950 era maps, but are below 200' rise on the newer metric maps. The Marshall's distance clause is the sole reason these mountains appear on the 46er list.
So I would not discount Yard Mountain merely because of its current 203' prominence from Big Slide. It is in the same company with 6-8 of the 46er peaks. As Tom noted it is on the Northeast 3000' list of 770+ mountains.
To understand why the Marshall brothers and Herbert Clark overlooked Yard, one needs to look at their maps. You can view and/or download these maps at the University of New Hampshire's repository of
Historic USGS Maps of New England & NY. Go into the Quad Index for New York and look for the 1895 Mount Marcy, 1898 Lake Placid, 1901 Elizabethtown, 1904 Santanoni USGS quads.
On the
1895 Mount Marcy Quad, the 4038' Yard was unnamed. It only had a 118' rise/prominence from Big Slide. I had originally thought that it had less than 0.75 mile from Big Slide on this map, and thus it failed both criteria and was rightfully excluded from the Marshall/Clark list of 4000' peaks. However, on closer examination it is clear that Yard was more than 0.9 mile from Big Slide on the 1895 map. So it appears that the Marshall brothers probably overlooked Yard because it was unnamed. Yard did indeed qualify for their 4000' list on the 1895 map using the Marshall brother's criteria. On the
1953 Mount Marcy Quad the 4018' Yard fared much better with a 238' rise/prominence and about the same 0.9 mile distance from Big Slide. This was not the only oversight that the Marshall's made. They also overlooked Little Marcy and another northwest peak of Marcy which were also unnamed on the 1895 map, but both qualified under the distance clause. There were probably other overlooked, qualifying (distance clause) peaks on the 1895-1904 maps.
If the Marshall brothers and Herbert Clark had had access to the 1950 era or the current maps, they would have included Yard (> 0.75 mile) and the 4308' middle/east peak of Table Top (> 300' rise) on their list. They might have also included the 4744' Little Marcy and the 4406' northwest peak of Marcy which are both more than 0.75 mile from their respective next higher peaks (Marcy and Little Marcy), and both have more prominence than Gray and Armstrong, although neither has a 200' rise/prominence. They might have also stuck to their original assertion that Gray Peak should not be on the list as it failed (and continues to fail) both of their criteria on their and all subsequent USGS maps. The only reason that they reluctantly included Gray Peak of their final list of 46 was that Russell Carson politicked them into including Gray because it was named in honor of the Asa Gray, a native of New York and a prominent Harvard University botanist. But I would like to believe that if the Marshalls had the option to reformulate their list based on current knowledge; they might have avoided the distance clause altogether. Distance clauses are not used much in the formulation of current peak lists as they are rarely well defined and they lead to too many disputes and/or oversights on which "ridge bumps" to include on the peak list.
