Nature & Science
As the first national park set aside to “preserve the works of man,” Mesa Verde National Park also contains a rich diversity of natural resources worthy of national park status. The park includes 8,500 acres of federally designated wilderness, and is a Class I air shed, the highest standards set by Congress under the Clean Air Act. Park Mesa, in the southeast section of the park, has been designated a Research Natural Area. Research Natural Areas are managed to maintain the natural features for which they were established, and to maintain natural processes. They are excellent areas for studying ecosystems or their component parts and for monitoring succession and other long-term ecological change.
Mesa Verde (Spanish for green table), occupies just over 52,000 acres of the Colorado Plateau. The correct geological term for the area is cuesta. Cuestas are similar to mesas, but instead of being relatively flat, they gently dip in one direction. Mesa Verde is inclined slightly to the south at about a seven degree angle and has been highly dissected by wind and water erosion into a series of canyons and “mesas.” Elevations range from about 6,000 feet in the canyon bottoms near the southern park boundary to 8,572 feet at Park Point, about ten miles north.
Visible geologic formations in the park date to the late Cretaceous Period, from 90 million to 78 million years ago, and consist largely of sandstones and shales. The three youngest of these formations – the Cliff House, the Menefee, and the Point Lookout – are known collectively as the Mesa Verde Group. Also present are several dikes of intrusive igneous rock, as well as river gravels, transported from nearby mountains, which were used by the Ancestral Puebloans for tools.
Mesa Verde lies in the transition zone between the arid scrublands to the south and the forested montane environment of the Rocky Mountains to the north. The climate is semi-arid, with an average annual precipitation of 18.4 inches. The park supports four major plant communities. At the lowest elevation is the shrub-steppe community that includes sagebrush valleys. Then as you gain elevation, you move through pinyon-juniper forests, to mountain shrub communities, and finally to areas of Douglas-fir and Ponderosa pine. Each environment has characteristics that favor certain plants while limiting others. For instance, prickly pear cactus can be found on dry, sunny, rocky soils, whereas Douglas-fir is found in shaded, moist areas with deeper soils. Numerous seep springs created from the juncture of Cliff House sandstone and Menefee shale provide microclimatic conditions for more moisture loving plant species such as mosses and ferns.
Since Mesa Verde has experienced a number of wildfires in the last decade, there is also an opportunity to witness the role fire plays in resetting plant communities. For instance, pinyon-juniper woodlands usually turn over every 400 years. During a visit to the park you may notice burned pinyon-juniper environments that are currently dominated by grasses and weeds. Although seedlings are returning, it will take centuries for a mature pinyon-juniper forest to return to these areas. In the mountain shrub community, which takes up to 100 years to fully mature, Gambel oak has begun to resprout and is already making a come back.
The habitats support a great diversity of wildlife including resident and migratory mammals, birds, reptiles, amphibians, fishes, and invertebrates. Because of Mesa Verde’s protected status, many plant and animal species that have disappeared or are rarely seen in the region still exist at the park, including breeding pairs of peregrine falcon (Falco peregrinus) and Mexican spotted owl (Strix occidentalis lucida). Many species of rare plants survive on protected park lands. Some of these rare plants, such as the Cliff Palace milkvetch (Astragalus deterior), are endemic to Mesa Verde and are found nowhere else.