Topographic prominence

The key col for Aconcagua, if sea level is disregarded, is the Bering Strait at a distance of 13,655 km (8,485 miles).

This land bridge is the key col of the subject peak, and the peak's prominence is its elevation from that key col. Prominence is interesting to many mountaineers because it is an objective measurement that is strongly correlated with the subjective significance of a summit.

In the contiguous United States, the famous list of "fourteeners" (14,000 foot / 4268 m peaks) uses a cutoff of 300 ft / 91 m (with some exceptions).

If there are many higher peaks there are various ways of defining which one is the parent, not necessarily based on geological or geomorphological factors.

In terms of the falling-sea model, the two contours together bound an "island", with two pieces connected by an isthmus at the key col.

For example, the encirclement parent of Mont Blanc, the highest peak in the Alps, is Mount Everest.

Mont Blanc's key col is a piece of low ground near Lake Onega in northwestern Russia (at 113 m (371 ft) elevation), on the divide between lands draining into the Baltic and Caspian Seas.

Using the encirclement definition, the parent of almost any small hill in a low-lying coastal area would be Ben Nevis, an unhelpful and confusing outcome.

Using prominence parentage, one may produce a "hierarchy" of peaks going back to the highest point on the island.

In general, the analysis of parents and lineages is intimately linked to studying the topology of watersheds.

Alteration of the landscape by humans and presence of water features can give rise to issues in the choice of location and height of a summit or col.

[4][7] Other sources of data commonly ignore human-made alterations, but this convention is not universally agreed upon; for example, some authors discount modern structures but allow ancient ones.

Another disagreement concerns mountaintop removal, though for high-prominence peaks (and for low-prominence subpeaks with intact summits), the difference in prominence values for the two conventions is typically relatively small.

It is only with the advent of computer programs and geographical databases that thorough analysis has become possible[citation needed].

At a slightly lower level, the continents would still be connected and the high point of the combined landmass would be Aconcagua, the encirclement parent.)

A hill in a low-lying area like the Netherlands will often be a direct child of Mount Everest, with its prominence about the same as its height and its key col placed at or near the foot of the hill, well below, for instance, the 113-meter-high key col of Mont Blanc.

Wet prominence assumes that the surface of the earth includes all permanent water, snow, and ice features.

In a dry Earth, the lowest contour line would be the deepest hydrologic feature, the Challenger Deep, at 10,924 m depth.

[14] The dry prominence of Aconcagua is equal to its wet prominence (6960 m) plus the depth of the highest submerged col of the Bering Strait (about 40 m), or about 7000 m. Mauna Kea is relatively close to its submerged key col in the Pacific Ocean, and the corresponding contour line that surrounds Mauna Kea is a relatively compact area of the ocean floor.

Even just surrounding Afro-Eurasia would run a contour line through the Bering Straight, with a highest submerged col of about 40 m, or only 8888 m below the peak of Everest.

As a result, Mauna Kea's prominence might be subjectively more impressive than Everest's, and some authorities have called it the tallest mountain from peak to underwater base.

Contrast between topographic isolation and prominence
Figure 1. Vertical arrows show the topographic prominence of three peaks on an island. The dashed horizontal lines show the lowest contours that do not encircle higher peaks. Curved arrows point from a peak to its parent.
Topographic prominence of three peaks located in Maine , US, all near the higher Great Pond Mountain . Red triangles mark the four peaks, the lowest contour line encircling each of the three lower peaks are shown in black and the green dots mark the key cols that mark the starting point of prominence. The prominences are Atkins Hill: 430 − 310 = 120 ft, Cave Hill: 570 − 530 = 40 ft, Mead Mountain: 671 − 530 = 141 ft. The parent peak of each peak is Great Pond Mountain.
Figure 2. Showing two closed contour lines meeting at Peak A's key col.
Figure 3. Diagram of a mountain range showing peaks and cols, from which mountain parentage and prominences can be determined.
Chart showing relationships between the 100 peaks with highest prominence on Earth. (In the SVG version , hover over a peak to highlight its parent(s) and click it to view its article.)