On the east side of the source of East River are red beds in their full development, and on the summit the quartzites, yellow, drab, and brown, varying in intensity, depending upon the amount of heat to which they have been subjected.
Annual Report for the 1873 Field Season (Hayden 1874, 65)
The black clays of the Cretaceous extend up Gothic Peak [sic] more than half-way above the bed of the stream, 1,000 feet or more. Near the top of the shales there is a band of trachyte which extends through the peak.
Annual Report for the 1873 Field Season (Hayden 1874, 65)
Gothic Mountain (12,625 feet) is an impressively massive mountain when viewed from this angle. It was drawn from across the East River to the east on a rocky hill slope above the valley. The small settlement of Gothic just below the mountain has been the home of the Rocky Mountain Biological Laboratory since the 1930s.
In the “View up East River” the perceptive viewer will notice that one cannot actually see the East River in the drawing. It is hidden by the low, rounded hills on the left side of the sketch. The one waterway that does show is the relatively deep valley of Perry Creek—one of the large and vigorously eroding streams that head on the Whiterock Mountain mass. But the hidden nature of the East River in this view belies its significance. First, it is an important stream and one of the two rivers, the Taylor being the other, that merge several miles south of here at Almont to form the Gunnison River. The Gunnison is the largest tributary of the Colorado River in the state. Second, for lack of a more precise guideline, the East River could be used as the dividing topographic feature between the Elk Mountains and the West Elk Mountains directly to the west-southwest from here. The East River heads at Schofield Pass and runs in a wide valley underlain by the easily eroded Mancos shale. This shale, as we see in numerous cases, is a weak rock, and many valleys in western Colorado can attribute their existence to the soft shale and its erosive potential.
As we have seen with the sections on the Central Elk Mountains, section 12, and Teocalli and Italian Mountains, section 13, the Elks are primarily a sedimentary-rock-based mountain range. Certainly there have been many igneous intrusions and massive faulting along with folding, but the Elks are conspicuously composed of flat-lying sedimentary strata uplifted to high elevations. The West Elk Mountains are a different creature. They are almost all extrusive volcanics with huge ash flow and welded tuff formations and the geological chaos that comes from many separate volcanic events occurring over long periods in nearby locations.
In the East River drawing, the artist has sketched in the essential rock units as classified by the survey that comprise the higher parts of the scene on the right-hand side. All of the rocks with numerical designation and all those labeled as Cretaceous, Jurassic, Triassic, Carboniferous, and Silurian [sic] are sedimentary beds. The only intrusive unit included is a tertiary granite shown at the very top. As stated above, most of the Elks are flat lying—not so here. In fact, in the Annual Report for the 1873 field season, the rocks at (e) on the drawing have been determined to actually be folded more than ninety degrees, or overturned using the geologic nomenclature (Hayden 1874).
The dominant mountain in the scene is known as Benchmark White (13,401 feet) although the smaller, reddish peak (12,832 feet) in the foreground partially screens White. And White, in turn, hides the larger and much more prominent Whiterock Mountain [(g) on the drawing] that sprawls behind it and is mostly out of view. The Whiterock Mountain massif is really an expansive set of high peaks, many of which top 13,000 feet. Even nongeologists and nongeographers have picked up on this fact.
In the Guide to the Colorado Mountains put out by the Colorado Mountain Club, the author describes Whiterock Mountain as a “grandly rambling mass” and indicates the difficulty in climbing it because of the number of other high points that are located in close proximity and might obscure the routes to the main summit (Jacobs with Ormes 2000). The Hayden Survey puts the elevation of Whiterock Mountain at 13,563 feet. That number is probably in error (see the section on the San Miguel Mountains), but it is intriguing that there are so many conflicting elevations attributed to Whiterock Mountain in this modern era. Using several published maps and the internet, I found at least seven different elevations were claimed for the peak (13,318 feet, 13,401 feet, 13,402 feet [these last two are probably misidentified and are of White Mountain], 13,434 feet, 13,484 feet, 13,532 feet, and 13,539 feet). Usually, if there is a disputed elevation, it is within a few feet; here we have elevation estimates that are more than 200 feet apart. Even the US Geological Survey does not have an official spot elevation for Whiterock, but it lies between 13,520 feet and 13,560 feet as determined from the contours on the Gothic USGS 7.5-minute topographical quadrangle on which Whiterock Mountain sits.
The geology of the Whiterock massif is very different from that of the other Elk Mountains—even the name Whiterock Mountain provides a clue as to how different it is compared to its very near Elk Mountain neighbors. The white of the mountain comes from the white to light-grayish granite intrusion that nearly bisects the top of the peak. This intrusion came when the peak was at much lower elevation and subsequent uplifting placed the granite at the 13,000-plus-foot level. The surrounding sedimentary strata have subsequently eroded away. A modern geologic map indicates the granite is a similar chemical/mineral composition to other intrusions that have taken place in the vicinity (see the section 13, on Teocalli and Italian Mountains). The rock, identified as granite by Hayden and crew, grades from a true felsic granite with high quartz content and acidic pH to diorite, which is much less acidic, contains significantly less quartz, and has a higher percentage of feldspars and other minerals such as biotite. The diorite is classed as an intermediate intrusive rock.
Gothic Mountain (12,625 feet—everyone seems to agree on the elevation) is on the far left and slightly in the background of the drawing. The separate drawing of “Gothic Mountain, Elk Range” is a much better view of this beautiful peak. It sits just west of the East River and the low ground in the sketch/photograph foreground is the East River Valley. The geology here is quite different from Whiterock and its surrounding landscape. Although the Hayden Survey indicates that Gothic Mountain is in the Elk Range, it is really in the transition zone between the Elks and the West Elks.
The East River runs through the weakly consolidated Mancos shale, but Gothic Mountain also sits directly on top of this weak rock. So, how can we have a 12,000-plus-foot mountain supported by such an erodible rock formation? The same sequence of Tertiary igneous intrusions occurred with Gothic Mountain as we see across the valley on Whiterock Mountain and on Italian Mountain. The difference is that the chaotic folding and faulting of the sedimentary beds during the intrusion did not occur on Gothic. A great sill of igneous material is visible on the Gothic Mountain scene. About halfway up the mountain there appears a thick, horizontal palisade-like structure. This sill caps the shale, and since the igneous rock is much more resistant to erosion, it protects the shales below from rapid erosion. The mass of the mountain above the sill is an even-larger injection of igneous rock called a laccolith. A laccolith is a small version of a massive batholith—a huge injection of molten material such as occurs in the Pikes Peak region. The laccolith is much more voluminous than the sill, and the high elevation of Gothic is preserved by this tough rock cap.
The mountains bordering the East River Valley from Schofield Pass all the way to Crested Butte just a few miles south of Gothic are a somewhat unique geomorphic environment that results from the juxtaposition of the intrusives above and the shales below. The erosion-resistant igneous intrusions protect the easily erodible shales below—somewhat. The shale is so soft that it can erode, albeit more slowly than it would otherwise, as water reaches it from rain, snowmelt, or even from flooding of the river. As the shale slowly gets eaten away from underneath the sill, the hard, but not invincible, igneous rock loses its support from below and eventually falls or slides away in a mass wasting event we usually call a landslide. This scenario is so ubiquitous in the East River Valley that a major study of it was conducted by Soule 1976 for the Colorado Geological Survey. Soule’s maps of the unstable slopes for this entire area should be a real eye-opener for anyone wishing to develop human activities/uses on any of the mountain slopes in the area. Gothic Mountain has no development on it at all, but Crested Butte, which has nearly the same geomorphic situation as Gothic, has considerable development. However, Crested Butte’s development has been precisely placed (so far) to avoid the landslides that are visible on the western and southwestern sides of the Butte and will continue to occur in the future.
At least one other feature of the Gothic Mountain drawing is interesting geomorphically. On the drawing you can see two rounded hills toward the bottom of the mountain. If you look at the photograph, you will not see these hills—at least as oversized as they appear on the sketch. The rounded mounds are really the runout zones of two massive avalanche chutes that come off of the mountain and run down the two major valleys that are obvious on both the drawing and the photograph. These are classic avalanche chutes, and the runout zones can be seen somewhat at the bottom of the mountain; however, they are mostly obscured by vegetation. Snow avalanches carry more than just snow with them. Vegetation, especially trees, can be uprooted and transported. If the avalanche is a full-depth one, any loose mineral sediment or rock can be dislodged and carried downhill. The runout zones of avalanches build up over thousands of years and countless avalanches to the “hills” depicted in the drawing and the fans shown in the photo.
The East River Valley and many of the other valleys in the area are avalanche prone in the winter. The combination of steep slopes developed from the landsliding and the large annual average snowfall create an environment that sprouts large numbers of snow slides. The ski runs at Mount Crested Butte ski area, for example, are positioned on the side of the mountain that has somewhat lower slope angles. The possibilities of more ski runs on the mountain are severely limited, and the ones that do exist are often steep, expert slopes. The slopes at Crested Butte are so severe that the mountain has hosted the winter X-Games, an extreme skiing event that demands challenging terrain. There are few beginner slopes at Mount Crested Butte.
The lack of easier slopes is now causing a major controversy in the area. Snodgrass Mountain, just between Gothic and Crested Butte, is an outlier for mountains here. It is gentle and rounded with easy slopes well suited for the beginner. The owners of Mount Crested Butte want to expand their operations to the US Forest Service–owned Snodgrass. Many local residents like Crested Butte’s reputation for extreme skiing and many others want to keep Snodgrass Mountain relatively wild with only a collection of cross-country ski trails on it. For now, at least, the US Forest Service has denied the expansion of skiing onto Snodgrass Mountain. But it remains to be seen if this is really the final decision.