> Warning - my interpretation! > SADDLE = low point between two high points (mountains), it does not > descend near the level of the adjacent valleys.
> PASS =A gap in a range of mountains or hills permitting easier passage > from one side to the other, it descends near the level of the adjacent > valleys. > This gives me a difference between 'pass' and 'saddle',otherwise they > appear to be the same? > If it were a 'pass' then that would make the range into two separate ways. > If it is a saddle then it does not break the range, but forms part of it. > Some mountain ranges do not have crest along their entire length .. yet > they are a mountain range along the entire length. 'Pass' is almost irrelevant to the observable geomorphology ( 'land forms' ) https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/geomorphology Pass is actually more of a 'route', similar to a nautical 'passage', which while it has a 'highest point' somewhere, may have several ups and downs. Some, like Big Hole Pass and Bridger on Montana State Route 287 are pretty much indistinguishable from the rolling flats around them, the mountains are in the distance. Some, in the American West are thousands of feet above the valley floors ( Beartooth Pass, Wyoming, USA ). The pass doesn't even necessarily route through a local minimum like a col, notch, or saddle, which frequently are canyons, but rather the shoulder of slopes. Further, there's a few that don't even connect adjacent watersheds, they weave between saddles of a crest, passing through multiple watersheds until finally dropping to a valley floor. There's a couple in Wyoming that more or less go over the peak of a single mountain. Ranges, paradoxically, aren't defined by the highest features like peaks and crests, they are distinguished from surrounding terrain by contiguous slope realms, usually back slope, foot slope, and toe slope. Basically, at whatever scale, there is a basal concavity ( http://bit.ly/2H9nn5O ) shared by higher elevations, which marks the transitions - in the case of the Cascades or Rockies, thousands of miles, in Montana sometimes tens of miles. Within the Rocky Mountain Range ( https://en.wikipedia.org/wiki/Rocky_Mountains ) which contain the Sawtooth Montain Range ( https://en.wikipedia.org/wiki/Sawtooth_Range_(Idaho) ). The Front Range of the Rocky Mountain Range consists of several smaller ranges - see https://en.wikipedia.org/wiki/List_of_mountain_ranges_of_Colorado#Mountain_ranges The central highest features of a range are perhaps helpful for labeling purposes, but don't really define the mountain range - it is an area. In less dramatic ranges, sometimes it's easier to look at the interfluves ( https://en.wikipedia.org/wiki/Interfluve ), like for https://www.ndhorizons.com/articles/29/summer-2006-north-dakota-s-mountains.aspx Also, 'saddles' are only one very specific type of local minimum between peaks that have two orthogonal continuous curvatures at a local minimum and maximum. There are other geomorhological terms like cols, notches, that account for discontinuous situations ( https://en.wikipedia.org/wiki/Col ). There already exists classification keys for these landforms which are used in automated terrain analysis. ( see the classic https://www.asprs.org/wp-content/uploads/pers/1993journal/sep/1993_sep_1409-1417.pdf , which validated the defining features mentioned above against the existing nomenclature, and the links on http://www0.sun.ac.za/cga/portfolio-items/terrain-analysis/ ). Michael Patrick Data Ferret OSM Seattle
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