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Ferrocement or ferro-cement [1] is a system of construction using reinforced mortar [2] or plaster (lime or cement, sand, and water) applied over an "armature" of metal mesh, woven, expanded metal, or metal-fibers, and closely spaced thin steel rods such as rebar. The metal commonly used is iron or some type of steel, and the mesh is made with ...
The iron cycle is an important component of the terrestrial ecosystems. The ferrous form of iron, Fe 2+, is dominant in the Earth's mantle, core, or deep crust. The ferric form, Fe 3+, is more stable in the presence of oxygen gas. [22] Dust is a key component in the Earth's iron cycle.
The advantage of ferrocement construction is that materials are cheap and readily available, while the disadvantages are that construction labor costs are high, as are operating costs. (Ferrocement ships require thick hulls, which results in either a larger cross-sectional area that hurts hydrodynamics, or leaves less space for cargo.)
the Earth's mass, its gravitational field, and its angular inertia. These are all affected by the density and dimensions of the inner layers. [20] the natural oscillation frequencies and modes of the whole Earth oscillations, when large earthquakes make the planet "ring" like a bell. These oscillations also depend strongly on the inner layers ...
The De Virga world map was made by Albertinus de Virga between 1411 and 1415. Albertin de Virga, a Venetian, is also known for a 1409 map of the Mediterranean, also made in Venice. The world map is circular, drawn on a piece of parchment 69.6 cm × 44 cm (27.4 in × 17.3 in). It consists of the map itself, about 44 cm (17 in) in diameter, and ...
A tumulus or barrow is a mound of earth created over a tomb. [10] A cross dyke or cross-ridge dyke is a bank and ditch, or sometimes a ditch between two banks, that crosses a ridge or spur of high ground. Found in Europe and often belonging to the later Bronze Age or Iron Age. [11] Often marked on Ordnance Survey maps in the UK. [12]
The oldest dated rocks formed on Earth, as an aggregate of minerals that have not been subsequently broken down by erosion or melted, are more than 4 billion years old, formed during the Hadean Eon of Earth's geological history, and mark the start of the Archean Eon, which is defined to start with the formation of the oldest intact rocks on Earth.
Earth's outer core is a fluid layer about 2,260 km (1,400 mi) thick, composed of mostly iron and nickel that lies above Earth's solid inner core and below its mantle. [ 1 ] [ 2 ] [ 3 ] The outer core begins approximately 2,889 km (1,795 mi) beneath Earth's surface at the core-mantle boundary and ends 5,150 km (3,200 mi) beneath Earth's surface ...