The zip line grounds are home to many interesting creatures and also, to some incredible rock formations. The most eye-catching of them all, of course, are the dramatic rocky cliffs. Here, layers of sand and rock have been deposited over millions of years, and then subjected to geological forces that led to an “uplifting experience” of sorts. The result is a lofty outcropping of colorful rocks, compressed into wavy ribbons of subtle tans and earthy vibrant oranges.
Less obvious—but nevertheless having their own story to tell—are the zip line’s travertine rock formations, remnants of once-thriving mineral hot springs. These deposits provide clues to the past environments of this region.
Zip line guests have the opportunity to hike past the travertine formations and also to take a piece of travertine in their hands, turn it over, and study it carefully. If they look closely, they may also see “soda straws,” the actual vessel through which the waters of the hot springs flowed. In its natural, untouched form, this rocky “historical record” of times past is, in many cases, rather ordinary. But once polished, it becomes a true beauty.
Not all travertine-in-the-raw is ordinary in apperance, however. Perhaps the best example of this is the travertine in Yellowstone Park. The Park’s Mammoth Hot Springs are home to astonishing travertine formations, complexes of hardened mounds of multihued quasi-rock, heaped up like generous helpings of ice cream scoops, and enveloped in a steamy fog. The sight is nothing short of a mystical cosmos.
Yellowstone’s other-worldly travertine formations easily overshadow their lesser counterparts, found in many places throughout the United States as well as other places throughout the world. The natural production of this stone starts with mineral springs, usually hot springs. Again, think “Yellowstone.” Geothermally heated waters, rich in carbon dioxide, percolate through rocks in limestone areas, dissolving the limestone. Limestone is simply calcium carbonate—and thus, these waters becomes saturated with this material. Later, when the water resurfaces, there is a rapid drop in pressure along with a change in temperature; these factors cause the water to release its carbon dioxide, similar to what one would see with “fizzy drinks.” As the carbon dioxide concentration decreases, the pH increases (becomes more alkaline). The calcium carbonate then precipitates, or recrystallizes. These precipitants oftentimes form over tiny underwater plants. Given the chemical processes that lead to travertine formation, it should be no surprise that the rock which results is characteristically porous.
The color of travertine stone can vary from tan to brown, and typically has swirls of earth-tone colors. Pure travertine is white; coloration is due to impurities in the process of travertine formation. Besides the chemical process leading to travertine formation, the porous nature of this stone is in part due to the actions of bryophytes (small plants that grow in tight masses such as mosses), algae, cyanobacteria (use photosynthesis to create their own energy), and other bacteria. These organisms catalyze the process of mineralization.
In addition to the presence of suitable plants, there are a number of other factors that can enhance the saturation of water with calcium carbonate and thus facilitate travertine formation. Air turbulence, such as that seen with waterfalls, can do so as can the process of evaporation. These factors all lead to reduced carbon dioxide concentrations and thus precipitation of calcium carbonate.
Besides its association with hot springs, travertine is also found underground in limestone caves. Precipitates of calcium carbonate form the commonly found stalactites, or dripstones, as well as the stalagmites that form from the floor upwards in these caves.
Travertine is used extensively as a buidling material. It is used as countertop material, in flooring, and also has ornamental uses. Its natural non-skid surface makes it a very desirable floor surface. Many famous buildings were constructed using extensive travertine materials—Chicago’s former Sears Tower, the Department of Commerce building, and the Roman Coliseum are just a few examples. In the latter case, this building is the largest of its kind that was made primarily from travertine.
Ancient Egyptians used travertine for construction as well as for ornamental purposes. Vases and statues were oftentimes made of this rock. The Egyptians found that this stone was rather easy to carve, especially when fine details were called for. The “alabaster” artifacts from this period were actually made of travertine given its ease of workability.
Aside from manmade creations using travertine, there are other famous natural travertine formations. Dramatic waterfalls can be seen at Oklahoma’s Turner Falls, the tallest falls in the state. There seems to be travertine everywhere here—the falls, the upstream and downstream waterway shelves, and a travertine cave tourist attraction. Travertine waterfalls can also be found outside of the United States, one example being Tivoli, Italy.
Of non-US countries with travertine deposits and formations, Italy is one of the most famous. Ancient Romans quarried this rock extensively, using it to build the Coliseum. The travertine name itself was derived from Tibur, an ancient Roman town. Tibur stone (stone was known as lapis tiburtinus) became corrupted to its current name, travertine.
A much softer and more porous rock that is made by the same processes as those leading to travertine deposits is called tufa. This rock forms in waters that are at ambient temperatures.
Travertine deposits in Colorado
The Captain Zipline grounds sit in a region that is considered to have the largest deposits of travertine in the state of Colorado. Specifically, the area is that of Wells Gulch, straddling the border between Fremont and Chaffee Counties. Chunks of travertine weighing up to 100 tons have been excavated from this site. It is an area that is rich in other materials as well—manganese, calcite, jasper, and rare earth minerals are found here. But even more interesting is that evidence of past life forms preserved in rock (fossils) can be found here. Paleozoic-era fossils from 300 million to 545 million years ago are known to be present in this fascinating area of central Colorado.
Of course, we are thrilled when our guests take an interest in the natural treasures that abound at the zip line. It’s only “natural,” then that we feel compelled to return the favor and offer our zip line guests a “thrill-of-a-lifetime.”