September 28, 2019

Searching for the “biggest” mountain in the Appalachians…and why is “biggest” in quotes?

Posted by larryohanlon

By Philip S. Prince, Virginia Tech Active Tectonics and Geomorphology Lab

A recent visit to Cattail Peak (6,583 ft/2,006 m), a summit in North Carolina’s Black Mountains, left me wondering where the most topographically prominent peaks and biggest possible summit climbs in the Appalachians are located. Cattail Peak is located just northeast of Mt. Mitchell, the highest peak east of the Mississippi River (6,684 ft/2,037 m), and as a result does not receive much attention unless you happen to hike across its summit. Despite being overshadowed by the elevation of its larger neighbor (which also has a nice road to the top), Cattail Peak could be called the most prominent summit of the Black Mountain range, meaning it rises the farthest above the nearest valley. If you set out from a point on Rock Creek at the eastern foot of the Black Mountains and walked a punishing straight-line path to Cattail Peak, you would climb about 3,700 ft (1,128 m) in 2.5 miles (~4 km). Despite being taller, Mt. Mitchell is a bit further removed from low elevation valleys and thus is not quite as prominent over short or moderate distances.

Mt. Mitchell is higher, but there is more relief over 2.5 miles (yellow line) from Rock Creek to Cattail Peak. If you drew a longer line from Mt. Mitchell, it would ultimately exceed Cattail’s relief, but I was interested in the obvious valley-to-peak climb that one can visualize from the cliff tops at Cattail’s summit.

Out of geologic interest and an admitted desire to know where the most impressive Appalachian straight-line climbs could be found, I compared Cattail Peak’s numbers to some other high and prominent Appalachian summits to see how they measure up. This isn’t a “top 5” list; it is more intended to show the zones of biggest relief throughout the Appalachian range. Note that the distance I use is clearly arbitrary; it’s based on Cattail Peak, where I happened to be, and the distance from that particular peak to an obvious valley starting point below. Conveniently, however, looking at topographic relief within a 2.5 mile radius allows an undisputed “biggest mountain to climb” (in terms of prominence and how much a hiker could climb in 2.5 miles…why “biggest” is in quotes) in the Appalachian range to be named. The few possible candidates within the entire range also make this a fairly easy question to answer. Increasing the distance from the summit beyond 2.5 miles changes the “biggest” result, but all of the mountains in question end up showing interesting similarities in terms of physical proportions.

The method is simple, but I feel pretty good about the results. I looked for the lowest elevation within a 2.5 mile radius of the high point (Cattail Peak is marked by the red pin in the center of the circle). The black line connects the low point to the high point and is the path of maximum relief over 2.5 miles. River layouts make the process easier in the southeast. The Cane River headwaters to the west of the ridge are higher than the Toe River headwaters to the east, so you already know on which side of the mountain to seek the lowest point in the search circle.

I usually try to avoid facts and trivia on this blog, but because mountain height and topographic relief are the result of combined influences of tectonic process, bedrock type, river system layout, climate history, and many other factors, I think there is enough geologic relevance. I also include a word on some geologic trends seen in the highest East Coast mountains, and (to the certain delight of readers in Mountain and Pacific time zones) offer comparison to a western mountain range.

  1. Cattail Peak (6,583 ft/2,006 m) 3,700 ft elevation gain in 2.5 miles

    Cattail Peak is just left of center; the peak closer to the left of the image looks higher because it is closer. View is up Middle Creek valley towards the summit.

    Cattail Peak originally caught my eye from the valley below. It creates a very rugged, rocky, and “un-Appalachian” skyline when viewed from the Toe River. It’s also only a couple miles away from the east coast’s highest summit, Mt. Mitchell. The steepness and relief of Cattail peak are interesting because it is very “insulated” from much lower elevation valleys outside of the highest parts of the Appalachian Blue Ridge. Being removed from low elevation valleys typically supports overall high elevation in the Appalachian landscape, but does not promote elevation difference and associated steepness over the distance I am looking.

  2. Mt. LeConte (6,594 ft/2,009 m) 3,900 ft elevation gain in 2.5 miles

    View is up Porters Creek (left) and Long Branch (right). Messer Cabin is just above the confluence, slightly below center.

    Mt. LeConte will show up again later, and it unquestionably exceeds the prominence of Cattail Peak. In comparison to Cattail Peak, LeConte’s overall elevation is impressive because it is quite close to the much lower river valleys (valleys under 1,000 ft/300 m) of the greater Tennessee Valley. You can see this in the colorful shaded relief maps a few images down. This is a good scenario to produce rugged topography, but challenges the survival of the very high peaks and thus maximum topographic relief in a landscape like the Appalachians. One of the many high peaks within Great Smoky Mountains National Park, LeConte is exceeded in elevation by nearby Clingman’s Dome (6,643 ft/2,025 m), but Clingman’s Dome is too far removed from the Tennessee Valley to show greater topographic relief over 2.5 miles. Old Black, a peak above Cosby, Tennessee to the northeast, deserves an honorable mention within the Great Smoky Mountain range. It rises approximately 3,600 ft in 2.5 miles and is very similar to LeConte in its geology and position within the range.

  3. Grandfather Mountain (5,946 ft/1,812 m) 3,020 ft elevation gain in 2.5 miles

    View is up a headwater prong of Wilson Creek. The Blue Ridge Parkway is the highest road on the mountainside seen here. Linn Cove Viaduct is just below the rocky cliffs on the crest of the ridge.

    The numbers listed here are specifically for Calloway Peak, Grandfather’s highest point. I was obviously off the mark in picking this one, but I had to check it out because of where Grandfather is located within the Appalachian landscape. Calloway Peak sits right on the Eastern Continental Divide, meaning its southeastern slope has a very direct connection to low elevaiton (1,300 ft/396 m) valleys of rivers that flow across the Appalachian Piedmont to the Atlantic Ocean. The back side of the mountain drains across the elevated Blue Ridge to the Tennessee system and Gulf of Mexico. I figured this arrangement would be a good recipe for considerable relief, and I admit I am quite surprised by how it compares to the other mountains over the 2.5 mile distance. Despite not making the cut, Calloway Peak is the highest point on the Eastern Continental Divide, and a very interesting landform.

  4. Roan High Bluff (6,267 ft/1,910 m) 3,300 ft elevation gain in 2.5 miles

    View is up Broad Branch. I think this summit may not be accessible to the public.

    This is another surprising result, as I initially thought that the Roan Mountains are not high enough, are too far into the Tennessee River headwaters, and are too far removed from the Tennessee Valley to show high-end relief. Even so, Roan High Bluff at the southwest end of the Roan Highlands exceeds Calloway Peak’s numbers as well as the relief in the Balsam Ranges between LeConte and Asheville, NC. Interestingly (and probably not coincidentally), Roan High Bluff is drained by the same river system (Toe-Nolichucky) as Cattail Peak.

    Southeast of LeConte and southwest of Mt. Mitchell, the Balsam Ranges are another big block of 6,000 ft peaks. They are too far into the interior of the high Blue Ridge to meet or exceed the relief of LeConte or Cattail.

    This is it until you get to New England…nothing in the mid-Atlantic compares. There is very impressive steepness on the eastern side of the Blue Ridge in Virginia (The Priest and Peaks of Otter, for example), but they lack the overall elevation to compete. Heading northeast, the next contender (and Grand Champion in the 2.5 mile class) is Mt. Washington, in New Hampshire’s White Mountains.

  5. Mt. Washington (6,288 ft/1,916 m) 4,200 ft elevation gain in 2.5 miles

    Tuckerman Ravine is on the left; Huntington Ravine is on the right. Pinkham Notch and Camp Dodge are just about directly underneath the observers perspective. A few trails wind their way up this route.

    Mt. Washington unequivocally serves up the most elevation gain within a 2.5 mile distance of its summit of any mountain in the Appalachians. It could thus be considered the “biggest mountain” in the Appalachians, depending on your distance from it. While its overall elevation does not match the southeastern peaks, surrounding valleys are notably lower. The hiking trails to the summit from the Pinkham Notch complex cover the full 4,200 ft and then some, although on a slightly more forgiving path than the 2.5 mile straight line! Mt. Washington is interesting (and very distinct) from the southeastern high points for a number of reasons, but the most significant are its history of glaciation and its location entirely within the Atlantic slope. Compared to the high peaks of the southeast, it is remarkably close to the Atlantic Ocean.

  6. Mt. Katahdin (5,267 ft/1,605 m) 3,790 ft elevation gain in 2.5 miles

    The actual peak is behind the apparent summit ridge seen here. Because of glacial sculpting of the landscape, the maximum relief straight line does not roughly follow a stream channel or ravine straight to the summit.

    Mt. Katahdin is not particularly high, but the surrounding Atlantic slope valleys are comparatively quite low, making its prominence comparable to peaks 1,000 feet (300 m) higher. At shorter distance scales, Katahdin’s steepness is even more impressive. Like Mt. Washington, its history of glaciation sets it apart from the southeastern high points. The trail from Katahdin Stream Campground to the summit, typically the first or last day for Appalachian Trail thru-hikers, begins outside the 2.5 mile radius and gains about 4,200 ft elevation. As in the case of Mt. Washington, the proximity of Katahdin to the Atlantic is notable.

    The southern high points are much more insulated from sea level. Because rivers are a major control in setting landscape elevation, being farther from the ocean is conducive to preserving high elevation.

    Looking beyond 2.5 miles

    How do these relationships hold up if you look farther than 2.5 miles from the summits?

    Mt. LeConte moves to the top of the list. LeConte rises about 5,300 ft (1,615 m) above Gatlinburg, Tennessee over a distance of 5.9 miles (9.5 km). Mt. Washington rises 5,100 ft above a point on the Ellis River southeast of the summit over the same distance. LeConte rises about 5,500 ft above Pigeon Forge, Tennessee over a distance of 10 miles (16 km).

    The red line between LeConte and Gatlinburg is the 5.9-mile, 5,300 ft straight line. Clingman’s Dome is a bit higher, but more insulated from the low valleys. Green-colored valleys are about 1,000 ft or lower; yellow is 1,300-1,500 ft, and white begins around 3,000 ft.

    By comparison, Mt. Washington rises about 5,400 ft above the Androscoggin River in Gorham, New Hampshire over the same distance, so there really isn’t too much difference between it and LeConte at this scale. Katahdin is obviously out of the running here as it’s summit is not even 5,400 ft above sea level, and none of the other southeastern peaks can compare to LeConte and Mt. Washington because they are too far from low elevation valleys. As the distance considered stretches farther from the summits, Mt. Washington will ultimately regain the lead as the “biggest mountain to climb” because it is so much closer to the Atlantic Ocean, and thus sea level, than LeConte.

    Do the prominent mountains have anything in common?

    The easiest answer is that they are made of hard rock. Rock strength, or how easily rock is weathered and eroded, very strongly impacts the present appearance (and evolution) of the Appalachian Mountains. Exposures of hard rock make prominent topography, and larger, thicker exposures of hard rock make larger prominent areas that end up hosting the highest and most prominent peaks. If you poke around at geologic maps of the mountains in question, you will see the term “metagraywacke” several times. Graywacke is a type of sandstone that contains tiny rock fragments and minerals such as feldspar in addition to a large amount of quartz sand; metagraywacke is graywacke that was buried deeply enough in the Earth to be metamorphosed. Metagraywacke is strong due to its considerable quartz content; it is a physically hard rock that resists chemical weathering well. Metagraywacke exposures can also be extensive, as the original graywacke deposits can be quite thick prior to being metamorphosed and deformed during mountain building. In the Appalachians, if it’s really tough rock (which almost always means it has high quartz content) and there is lots of it, it will make high mountains that remain high as surrounding valleys are carved deeper. Cattail Peak, LeConte, Calloway Peak, and Mt. Washington are all to some extent supported by exposures of metagraywacke, along with other rocks.

    The rock-type control seen in the Appalachian Valley and Ridge isn’t so obvious here, but it’s still a major player. The red triangle (near upper left) is LeConte, the yellow circle is Asheville, North Carolina, and the blue triangle (upper right) is Cattail Peak. The thin black outlines encircle the 6,000 ft Balsams, whose elevation is still impressive. Different river system elevations can also be seen here. Asheville is located on the French Broad River, whose valleys are much lower than the Pigeon River immediately to the west. The Pigeon is also higher than the Little Tennessee to its west, and the Tennessee Valley streams (far upper left) and Atlantic Piedmont streams (far lower right) are the lowest of all. Green-colored Tennessee and Piedmont areas are about 1,000 ft above sea level, Asheville is 2,000 ft, and the Pigeon west of Asheville is about 2,600 ft. White areas are all above 3,000 ft, reaching the maximum 6,684 ft near the blue triangle.

    Roan High Bluff is just off the top of the map shown above. It is underlain by gneiss, which was also formed by metamorphism of sedimentary rock. Its overall mineral make-up is not too different from the metagraywacke bedrock of its high neighbors, allowing it to support very dramatic topography.

    Katahdin is underlain by granite, which can be a very strong and resistant rock type capable of supporting impressive topography (think Yosemite and the Sierras). Interestingly, some Appalachian granites produce high topography while others produce distinct topographic lows. This presumably results from how the granite weathers, which I would guess relates to subtle aspects of mineral composition (proportion of feldspar to quartz to mica, feldspar composition, etc.). Again, quartz content is a key player. In any case, like the other examples, Katahdin’s height and prominence obviously has some connection to rock type. Its extreme prominence despite its sub-6,000 ft elevation is also definitely connected to its geologically recent sculpting by glacial ice.

    Fluvial topography at left (Cattail) and glacial topography at right (Katahdin)…a very different look. These images are the same scale, and the red lines are the 2.5 mile maximum relief lines.

    Hard rock is obviously important, but it is only part of the overall elevation story. That story is a bit complicated to get into here, but it certainly invokes all of the aspects of geology mentioned at the start. I think you can say a lot about each of the peaks mentioned here by looking at bedrock under the mountain itself, weaker rocks that form neighboring valleys, how rivers draining the mountain connect to the region’s biggest rivers, and recent glaciation. It is also necessary to think about larger-scale factors, like the regional thickness of the Earth’s crust and recent (10s of million of years to present) surface uplift history. The clustering of high and prominent peaks in western North Carolina/East Tennessee and New England probably reflect these larger-scale controls, as does the lack of comparable peaks in the mid-Atlantic despite the availability of appropriate quartz-rich rock types.

    It can be useful to step WAY back and look at the location of the highest and steepest east coast topography. One interesting pattern to see here is how far the continental shelf (the light blue area) extends away from the coast line. In New England and the southeast, it reaches well away from the present coastline. In the mid-Atlantic, deeper ocean (dark blue) atop oceanic crust reaches further towards the coastline.

    The similarities of high summit elevations and maximum relief are also a reflection of the large-scale, long-term geologic background of eastern North America. On this part of the continent, summits reaching into the 6,600 ft range and developing ~5,400 ft of relief over 10 miles is the best you can do. The Smoky Mountains and White Mountains compare well in this respect, and all of the highest 2.5 mile relief values were fairly consistent. Go to a more tectonically active landscape, and you’ll find something different…

    Comparison to the Teton Range

    Yes, summit elevations and topographic relief are much larger in the American west due to a very different tectonic past and present. I choose the Teton Range for a comparison because it is developed on a very actively moving fault within an area that is already quite elevated due to high heat flow within the Earth’s crust.

    Obviously not North Carolina, New Hampshire, or anything else east coast. Grand Teton is just left of center.

    The summit of the Grand Teton reaches 13,776 ft (4,199 m), creating about 6,500 ft of topographic relief within 2.5 miles of map distance of the summit. The scale and steepness of this relief means that map distance and ground distance are actually different; relief is a bit under 6,000 feet is ground length is used instead. Either way, this topography is the result of active fault uplift. The rock is strong granite, but even weaker rocks would display impressive topography in an active fault setting like this one. While this is a locally extreme expression of active tectonic movement, the entire American West has experienced a more tectonically dynamic recent geologic past and is thus home to larger and steeper topography than anything on the east coast.

    This post was originally published on The Geo Models blog