Concretions :: essays research papers fc

Dating back to the 18th century concretions yield been cognise as geologic curiositys due to the various sizes, shapes and compositions. Concretions have also been thought to be dinosaur eggs, extra-terrestrial debris, human artifacts and animal and plant fossils. receivable to these curiositys I will try and enlighten you more than on these in the following by explaining the process in which they atomic number 18 formed and explaining virtually locations where they stub be be in bountiful outcrops.     The word "concretion" is derived from the Latin "con"-- nitty-gritty "together" -- and "cresco" -- meaning "to grow."      Concretions are hard compact accumulations of mineral matter and are found inside sedimentary rocks. Some examples of this are Sandstone and in some endure vol jackpotic rock. Concretions come in many different shapes and the most ordinary of the shapes is spherical or disk shaped. Concretions are the most varied-shaped rocks of the sedimentary world. The mood concretions come to be is the mineral matter concentrates around the nucleus of a host rock. The nucleus is often organic much(prenominal) as a tooth or leaf or shell or fossil. As the mineral matter concentrates around the nucleus it forms harder zones known as nodules.     Concretions are in truth odd in the sense that they very in size, shape, color and hardness. a good deal concretions are mistaken for bones, fossils, meteorites and otherwise odd objects. They can be so small that it requires a magnifying glass to be visible or as large as 10 feet in diameter and weigh hundreds of pounds. Concretions can also have somewhat of regular shapes such as boxes, blocks, matte disks, pipes, cannon balls and have even been known to resemble parts of a human body such as a foot or ribs.     Concretions are most commonly composed of calcite but sometimes can be composed of iron oxide or iron hydroxide such as goethite. But also concretions can be composed of other minerals ranging from siderite, ankerite, dolomite, pyrite, baryite and gypsum.     Concretions form in many different focal points. The box shape of some ironstone concretions most often depend on the way a sandstone or shale bed breaks up due to the action of weathering into regular blocks of various sizes. The way in which this separation takes place along natural planes of weakness in a rock such as a horizontal bed surface and vertical joints. Before this process of separation, as well as during the separation ground water soaks into the rock and circulates through the planes of weakness make the rock more porous.