Yosemite, Sequoia & Kings Canyon National Parks (Fodor's) - Fodor's [66]
Anticline: Movements of the Earth’s crust produce these upward-curving, convex folds when they push originally horizontal rock layers upward in one spot. The anticline slopes downward from the crest.
Arch: This type of window in a rock wall forms either through erosion, when wind and sand wear away the rock face, or through the freezing action of water. When water enters spaces or joints in a rock and freezes there, the expansion of the ice can crack off chunks of rock. The parks of southern Utah contain many arches.
Badlands: Much of the sedimentary rock that eroded from the Black Hills was deposited in South Dakota’s Badlands, along with ash from the volcanoes in the Yellowstone area. The wind blew and water flowed over the landscape, carving out huge buttes and cliffs in a process that continues to this day. In the relatively soft, half-hardened rocks, the elements also carved drainage channels with a distinctive V shape, creating a network of ravines and ridgelines. These formations are devoid of vegetation because erosion carries off seeds and roots. The amphitheater at Bryce Canyon National Park is another example of badlands.
Basin: A basin is depression in the ground that collects sediment. Within a basin there are often smaller anticlines and synclines. The Great Basin is an example of a geologic basin.
Biological Soil Crusts: Also known as cryptobiotic soil crust or biocrust, this black, bumpy stuff covers the ground throughout the Colorado Plateau. It is composed of cyanobacteria, green algae, lichens, fungi, and mosses that form a living cover on the ground. The crust stabilizes the soil and allows plants to germinate and root. If it’s destroyed or damaged, new plant life cannot grow. It can take an estimated 50 to 250 years for this living organism to completely repair itself.
The Black Hills: South Dakota’s Black Hills began as a mountainous landscape covered with limestone and shale sedimentary rock, but this covering gradually eroded away, exposing a granite face. Much of the sedimentary rock that eroded from the Black Hills was deposited in the Badlands.
Bridge: If a window through a rock has been created by (now-receded) water flowing beneath it, it is called a bridge. You can see many natural bridges in the Colorado Plateau, such as Hickman Bridge at Capitol Reef National Park.
Butte: A butte is what remains when a mesa erodes—a hill with a flat top and steep sides. You can see good examples of this formation in Glacier and Canyonlands national parks.
Caldera: Although it is the largest and deepest example, the bowl-shaped depression in which Crater Lake lies is only one of many calderas along the Pacific Rim. Created when volcanoes blow their tops, small caldera remnants lie atop Mount Rainier and Mount Baker, and a bigger one remains on Mount St. Helens, where its side blew out in 1980.
Canyon: A canyon forms when water and wind erode soft layers of the Earth’s rock crust. The hardness of the rock determines the shape of the canyon: a narrow, or slot, canyon generally results when the rock is the same composition all the way down and water runs through the crack. A steplike canyon such as the Grand Canyon forms when alternating soft and hard layers are eroded by wind and water, with a river cutting a narrow groove in the bottom of the canyon.
Caves: Caves—natural underground chambers—give you an opportunity to descend below the Earth’s surface and learn about the forces of heat and water upon rocks and minerals. Crystal Cave in Sequoia National park has excellent examples of stalactites and stalagmites. In South Dakota, Jewel Cave and Wind Cave, each with more than 100 mi of mapped passageway, rank as second and fourth longest in the world, respectively, and each is home to incredibly rare rock formations. In New Mexico, Carlsbad Caverns’ extensive cave