The texture of these red beds is very variable. Conglomerates varying from a fine pudding-stone to a coarse aggregate occur all through the mass, but are not continuous. The entire group indicates deposition in disturbed waters. In tracing a bed horizontally sometimes it will thicken to a massive fine sandstone, then gradually thin out, and in its place soft, yielding shales appear.
Annual Report for the 1873 Field Season (Hayden 1874, 61)
If there were a single mountain scene in Colorado that everyone could agree was the most photogenic and the biggest tourist attraction, the landscape drawn here by William Henry Holmes might be a good choice. The Maroon Bells are arguably the most photographed mountains in the entire western United States. Most of these photos, unfortunately, are merely taken from near the parking lot that serves Maroon Lake and the trailhead to the Bells. Many people take this iconic shot, get back into their cars, and go to the next stop on the tourist route knowing that they have the requisite photo needed of the Colorado Rockies.
The view drawn by Holmes takes a bit more effort to see, but the rewards are worth the sweat. To get to the site you must hike up to Buckskin Pass and then ascend the adjacent 13,370-foot-high Buckskin benchmark to get the view. But once the four-hour or so hike is made, what a view it is—so close to the Maroon Bells (Maroon or South Maroon Peak—14,156 feet and North Maroon Peak—14,014 feet) [(c) on the panorama]—you feel you can almost touch them, but also expansive enough to take in the high mountains from Castle Peak (14,265 feet) (a) to the south all the way to Mount Sopris (12,953 feet) (k) to the northwest. This extravagant panorama encompasses so much rugged terrain that it could be used as the state’s official “spectacular view of the mountains.” A small irony, though, is that this revered set of mountains is really not geologically typical of the Colorado Rockies. As discussed below the natural history of the Elk Mountains is far different from that of most of the main mountain ranges in the state.
Aside from the San Juan Mountains of far southwestern Colorado, the Elk Mountains are the most extensive mountain system in the Southern Rockies. The Elks are also devoid of an abundant road network that might penetrate into the heart of the range. Part of the reason for this lack of four-wheel, motorized access is the rugged nature of the terrain with steep climbs to the passes and narrow, rock-debris-clogged valleys. The Central Elks are also the home of a large designated wilderness area—the Maroon Bells–Snowmass Wilderness Area, which includes 181,117 acres of high mountains, stark alpine landscapes, and innumerable high-gradient streams. This wilderness area is just one of several that make up a large, nearly contiguous road-free zone. The Raggeds, West Elk, and Collegiate Peaks Wilderness Areas along with the Maroon Bells–Snowmass create what could be called a supersize wilderness region in this part of the state, and a superlarge roadless area precludes anything but hiking and cross-country skiing.
The Maroon formation, from which the core red-bed mountains of the Elks are made, is actually the reincarnation, at least the recycling, of the Ancestral Rockies. The ancient uplands in Colorado consisted of two main mountain chains. The Front Range highlands (some call this Frontrangia) ran north-northwest to south-southeast across central Colorado, and the Uncompahgre highlands ran parallel to them but about a hundred miles to the southwest. As the two parallel mountain systems rose around 300 million years ago, they created a large lowland between them. This lowland filled with sediment coming off the rapidly rising and eroding mountains. The Maroon formation consists of the detritus of these old mountains and includes up to 7,000 feet of old streambeds choked with sand and gravel from innumerable alluvial fans that formed at the bases of the old mountain systems. The reddish/maroon color of the Maroon formation comes from the oxidation of iron-containing minerals in the rock—composed of ferric oxide, otherwise known as rust. Two related rock formations exist on the eastern side of the Front Range uplift and on the western edge of the Uncompahgre uplift—these are the Fountain formation and the Cutler formation respectively. They are the result of similar timing and processes that we see in the Maroon formation rocks.
Eventually, the Ancestral Rockies eroded away, and the entire area that is now the state of Colorado was reduced in elevation enough that seas invaded and receded periodically. The only evidence of the old mountains was the rock debris that became the Maroon, Fountain, and Cutler formations. But in the late Cretaceous, renewed mountain uplift came to Colorado. The Laramide orogeny (about 65 million years ago) raised most of central and western Colorado to new heights. The Maroon formation went from being valley sediment to forming some of the highest mountains in the state. Subsequent erosion and renewed uplift have left the Elk Mountains, including Teocalli Mountain (see section 13, “Teocalli/Italian”), at their present level. Recently, at least geologically speaking, magma rose through fractures in the sedimentary rock of the Elks. These Tertiary period magma intrusions produced some of the few nonsedimentary rocks dispersed throughout the Elk Mountain sediments. Some of these new, granitic mountains include Snowmass Mountain (14,091 feet), Capitol Peak (14,130 feet), and Whiterock Mountain. Smaller, numerous intrusions occurred throughout the Elks and have caused widespread contact metamorphism. This is why on a hike up to Buckskin Pass to get the sketch/photo viewpoint, one can find a wide variety of conglomerates, shales, slates, sandstones, quartzites, and even a few meta-conglomerates (conglomerates that have been metamorphosed).
The Hayden Survey knew little of this entire sequence. But survey members did recognize the significance of the rocks they surveyed. They realized the approximate ages of the sediments from the fossils found in them and hypothesized about the newer granite intrusions. Hayden, of course, did not have the sophisticated isotope chemistry techniques we now have for dating rocks absolutely, but he did know the general geologic principle of crosscutting relationships. This basically states that rock must be in place before another rock can cut across it by being injected into a crack, fissure, or joint. We see this here where the Maroon formation had the intrusive granite forced into it. Simply put, if the Maroon formation had not yet existed, the granite would have just spread out into a massive formation rather than into these narrower intrusions. It would take decades before the entire complex story of the Elk Mountains was finally pieced together, but given the comparatively rudimentary tools Hayden had, he and his crew did a remarkable job in describing the Elk Mountain Range.
Nearly the entire Elk Range was affected by glaciation during the Pleistocene epoch. The glaciers here were large and ran far down the valleys. For instance the glacier that ran in the Maroon Creek Valley went all the way to where the valley exits the mountain mass at the town of Aspen. The descriptions and explanations of glacial landforms and processes were discussed at length in the section on the View of the Sawatch Range, section 10, but a feature of glacial landscapes that is particularly prevalent in the Elk Mountains needs to be presented. These singular features are called rock glaciers. There are two genetically different types of rock glaciers: one is usually small and protrudes from the sides of former glacial valleys; the other is more interesting and at a much grander scale. This second type is part of the remnants of ancient ice glaciers that receded many thousands of years ago.
As a glacier retreats, the ice melts faster at the lower end of the valley and continues to do so until the terminal end of the glacier is near or even in the originating cirque. When the glacier was large and active, all the rock along the sides of the valley and at the cirque itself that weathered, eroded, and fell was mostly carried down valley and deposited far from its original source. But toward the end of glaciation when there is only the small remnant glacier—while this rock is still weathering, eroding and falling—there is little ice to carry it down the valley. As the rock debris begins to accumulate to greater and greater thicknesses, the small remnant glacier becomes insulated by the covering rock layer and does not melt. This ice can flow, but this time with massive amounts of broken and shattered rock lying as a hard blanket over the frozen core.
Mount Sopris is probably the archetype for rock glaciers on mountains throughout the western United States. Massive rock glaciers have accumulated and slowly descended several of its valleys. But large rock glaciers can also be found in many of the high mountain valleys in the Central Elks. In the drawing of the Central Elk range, there is a substantial rock glacier evident in the large cirque visible on Snowmass Mountain (14,091 feet) (h). Numerous other rock glaciers exist on the southern sides of the Maroon Bells and on many other peaks in the scene, but they are blocked from view by the mountains themselves. The vast amount of rock debris that has accumulated on all of these rock glaciers is a testament to the rapid (in relative terms) weathering and erosion of the Elk Mountains. You can easily recognize the slow, downhill movement of these massive rock conveyor belts. From above, they look like waves or ocean swells made of rock and ice. These dynamic marks of movement are quite elegant especially when you consider that they are formed from thousands of tons of jagged rock being moved by a relatively small amount of ice in concert with gravity.
Partly due to the beauty and the severity of the mountains in the Central Elk region, the range has become a locus for mountaineers. No mountain system in Colorado except for the San Juans is populated by such a density of high, challenging peaks. Other ranges have more 14ers, but no others outclass the climbing panache of the Elks. All of the loose rock already described above makes for a rigorous, demanding, and at times dangerous climb on most of these mountains. Climbers call it “rotten rock,” and the thought of it sobers even the most experienced alpinist. This makes the Elks one of the more hazardous ranges in Colorado, as they have claimed many lives—most mostly from those who fell when loose rock gave way at a precarious and inopportune time. Many, maybe most, of the peaks had not been climbed even by the end of the nineteenth century, and the Hayden Survey ascended only a handful of them. It was not until the early twentieth century that two local Aspenites started “bagging” the unclimbed peaks of the Elks. Percy Hagerman and Harold Clark conquered most of the main summits between 1908 and 1910. Hagerman wrote the most authoritative guide to these climbs with his Notes on Mountaineering in the Elk Mountains, 1908–1910 (Hagerman 1956). The rock, the climbing challenge, and the photogenic character of the Central Elk Mountains make this scene drawn by Holmes a classic of Colorado geology and mountaineering.