Sedimentary rocks are characterised by their formation from the deposition and lithification of rock material. They may be formed through physical and chemical processes, such as mechanical weathering, compaction and dissolving of rock material.Continue Reading
Sedimentary rocks may be formed through a process called lithification, which is the accumulation and compaction of sedimentary materials into solid rocks. Transportation through water systems such as rivers and oceans may cause clay, silt and other sedimentary materials to accumulate and form into rocks such as sandstone and shale. These rocks typically have smooth and rounded edges due to erosion from constant underwater motion.
Sedimentary rocks may be formed through the chemical dissolving and reforming of materials in rocks. Water sources that have a higher rate of evaporation than precipitation may facilitate the accumulation of sedimentary material, creating an environment in which the formation of new rocks becomes possible. Chemical weathering may cause materials such as calcium carbonate to accumulate and form new rocks such as limestone. Calcium carbonate is comprised of organic material, such as shells and coral, that have been broken down and dispersed in water sources and allowed to settle. The chemical properties of these rocks may be altered to form new rocks, such as dolomite, which is the result of limestone exposed to water containing magnesium.Learn more about Geology
Wind and rain erode rock to begin the formation of siltstone. The rock particles break down further as they travel with the water and then settle to the bottom of the water when it slows. Layers of silt accumulate, creating heat and pressure that cement the silt together into rock.Full Answer >
The principle of superposition in geology states that rock forms horizontally, with the oldest layers of rock lying at the bottom of a formation and newer rock resting on top. For instance, the Kaibab Limestone at the edge of the Grand Canyon is younger than the Toroweap Formation below it.Full Answer >
Water and ice cause weathering in rocks by causing bits of the rock to separate and flow away through the erosion process. While this process is extremely slow, it is also inexorable, and any stone object exposed to the elements disintegrates in this way.Full Answer >
Bauxite is a rock formed in wet, tropical climates when soluble materials leach into silica rocks. Bauxite is the principle ore from which most of the world's pure aluminum is extracted for commercial use. As of 2010, the largest producers of bauxite are Australia, China, Brazil, India, Guinea, Jamaica and Russia. Some of these countries have enough reserves for more than 100 years of aluminum production.Full Answer >