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Dutch Sand Ladder
A Dutch sand ladder is a cable or rope ladder with rungs usually made of wood, lying on a sandy slope to allow persons to ascend or descend with minimal erosion. Use of Dutch Sand Ladders in Fort Funston Fort Funston is a former harbor defense installation located in the southwestern corner of San Francisco. Formerly known as the Lake Merced Military Reservation, the fort is now a protected area within the Golden Gate National Recreation Are .... Illustrated. The bottom end is anchored and the top end is designed for easy disconnection so that the ladder can be lifted up to shake loose any sand that has accumulated on the rungs. The ability to be easily maintained and reset makes sand ladders useful trail features for steep sand dunes or other easily eroded areas where permanent structures are infeasible or impractical. References * Discussion of Dutch sand ladders, boardwalks, and other walkway constructions for sand dune access management, illustrated Hiking [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wooden Ladder To Help Climb Large Sand Dune On Desert Sands Trail, Spruce Woods Provincial Park, Manitoba
Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin that resists compression. Wood is sometimes defined as only the secondary xylem in the stems of trees, or it is defined more broadly to include the same type of tissue elsewhere such as in the roots of trees or shrubs. In a living tree it performs a support function, enabling woody plants to grow large or to stand up by themselves. It also conveys water and nutrients between the leaves, other growing tissues, and the roots. Wood may also refer to other plant materials with comparable properties, and to material engineered from wood, or woodchips or fiber. Wood has been used for thousands of years for fuel, as a construction material, for making tools and weapons, furniture and paper. More recently it emerged as a feedstock for the production ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ladder
A ladder is a vertical or inclined set of rungs or steps used for climbing or descending. There are two types: rigid ladders that are self-supporting or that may be leaned against a vertical surface such as a wall, and rollable ladders, such as those made of rope or aluminium, that may be hung from the top. The vertical members of a rigid ladder are called stringers or rails (US) or stiles (UK). Rigid ladders are usually portable, but some types are permanently fixed to a structure, building, or equipment. They are commonly made of metal, wood, or fiberglass, but they have been known to be made of tough plastic. Historical usages Ladders are ancient tools and technology. A ladder is featured in a Mesolithic rock painting that is at least 10,000 years old, depicted in the Spider Caves in Valencia, Spain. The painting depicts two humans using a ladder to reach a wild honeybee nest to harvest honey. The ladder is depicted as long and flexible, possibly made out of some sort of gr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Erosion
Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distinct from weathering which involves no movement. Removal of rock or soil as clastic sediment is referred to as ''physical'' or ''mechanical'' erosion; this contrasts with ''chemical'' erosion, where soil or rock material is removed from an area by dissolution. Eroded sediment or solutes may be transported just a few millimetres, or for thousands of kilometres. Agents of erosion include rainfall; bedrock wear in rivers; coastal erosion by the sea and waves; glacial plucking, abrasion, and scour; areal flooding; wind abrasion; groundwater processes; and mass movement processes in steep landscapes like landslides and debris flows. The rates at which such processes act control how fast a surface is eroded. Typically, physical erosion procee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fort Funston
Fort Funston is a former Seacoast defense in the United States, harbor defense installation located in the southwestern corner of San Francisco. Formerly known as the Lake Merced Military Reservation, the fort is now a protected area within the Golden Gate National Recreation Area (GGNRA). It was named in honor of Frederick N. Funston (1865–1917), a Major General in the United States Army with strong connections to San Francisco, and included several artillery battery, artillery batteries. The fort is located on California State Route 35, Skyline Boulevard at John Muir Drive, west of Lake Merced. The fort was constructed upon windswept headlands along the Pacific Ocean, Pacific coast and Ocean Beach, San Francisco, Ocean Beach below, above steep sandstone cliffs that provide a nesting habitat for a colony of bank swallows (''Riparia riparia''). The last remnants of a sand dune ecosystem that once covered the western half of San Francisco grows along the top of the headlan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sand Dune
A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, flat regions covered with wind-swept sand or dunes with little or no vegetation are called ''ergs'' or ''sand seas''. Dunes occur in different shapes and sizes, but most kinds of dunes are longer on the stoss (upflow) side, where the sand is pushed up the dune, and have a shorter ''slip face'' in the lee side. The valley or trough between dunes is called a ''dune slack''. Dunes are most common in desert environments, where the lack of moisture hinders the growth of vegetation that would otherwise interfere with the development of dunes. However, sand deposits are not restricted to deserts, and dunes are also found along sea shores, along streams in semiarid climates, in areas of glacial outwash, and in other areas where poorly cemented san ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
