Yosemite, Sequoia & Kings Canyon National Parks (Fodor's) - Fodor's [68]
Mesa: A hill with a smooth, flat, table-like top is a mesa, which means "table" in Spanish. It is a clear example of how hard rock stands higher and protects the soft rock beneath. A single mesa may cover hundreds of square miles of land. At the Island in the Sky District of Canyonlands National Park and at Mesa Verde you are standing on top of a mesa.
Monocline: The most notable geologic feature of the Colorado Plateau, a monocline is a bit like half an anticline (see above). The layers of rock on either side of a monocline are mostly level, but they bend downward like a step. Pioneers often called them "reefs" because the formations were a barrier to passage through the area. The Waterpocket Fold in Capitol Reef National Park is a most dramatic example of a monocline. Another example is the Monument Upwarp, which extends from Kayenta, Arizona, to the confluence of the Green and Colorado rivers in Canyonlands National Park. There are many smaller anticlines and synclines along the Upwarp.
Monument: This general term applies to geologic formations that are much taller than they are wide, or to formations that resemble man-made structures. You can see many examples of the first type of monument in Capitol Reef National Park’s Cathedral Valley; in Monument Valley, Arizona; and in the White Rim Monument Basin area at Canyonlands National Park. Monuments that fall into the second category include the Sinking Ship in Bryce Canyon National Park and the Three Penguins at Arches National Park.
Petrified Wood: If you want to know what the desert Southwest used to look like, picture the Florida Everglades populated with giant dragonflies and smaller species of dinosaurs. Arizona’s Petrified Forest offers a glimpse of the once lush, tropical world. Stumps and logs from the ancient woodland are now turned to rock because they were immersed in water and sealed away from the air, so normal decay did not occur. Instead, the preserved wood gradually hardened as silica, or sand, filtered into its porous spaces, almost like cement. Erosion was among the geological processes that exposed the wood.
Plains: Once home to vast herds of bison that blackened the prairie for miles, the grasslands across the nation’s center today serve as America’s breadbasket, supplying much of the nation and parts of the world with dairy products, grain, seeds, cattle, poultry, and pork.
Playa: Dry, salt-encrusted lake beds known as playas (“beaches” in Spanish) commonly lie in the low points of arid southwestern valleys. You can see examples in the Sonoran Desert near Tucson and in Death Valley National Park.
The Rocky Mountains: The Rocky Mountain chain reaches from northwestern Canada down through Washington, Idaho, Montana, Wyoming, Colorado, Utah, and into New Mexico. The huge mountains are thought to have been raised by massive tectonic plates colliding, pushing the Earth’s crust upwards. The soft rocks eroded and were split by deep fault zones, exposing the harder granite for which the mountains are known.
Sand Dunes: The sand dunes that you occasionally come across in the Colorado Plateau have been deposited by winds. Wind blowing past rock formations will pick up grains of sand. If the wind then passes through a natural channel like a window or a slot canyon, it will lose speed when the channel ends and the sand will drop onto the ground. Plants cannot grow in these dry, windy spots, so the wind continues to deposit sand, and a dune forms. Two good examples