Search results
Results From The WOW.Com Content Network
Main page; Contents; Current events; Random article; About Wikipedia; Contact us
Sphalerite has been found as a pseudomorph, taking the crystal structure of galena, tetrahedrite, barite and calcite. [13] [15] Sphalerite can have Spinel Law twins, where the twin axis is [111]. The chemical formula of sphalerite is (Zn,Fe)S; the iron content generally increases with increasing formation temperature and can reach up to 40%. [6]
Most fossils have been found in the southwestern United States, the majority coming from a geological deposit called the Red Beds in Texas and Oklahoma. More recently, fossils have been found in Germany. Over a dozen species have been named since the genus was firstdescribed in 1878.
Human fossils were discovered first by Aurora Martín Nájera; the 30 cm (12 in) layer they were found in is nicknamed the "Aurora Stratum" after her. [4] A 13 m 2 (140 sq ft) triangular section was excavated in the central section starting in the early 2000s. [3] Human fossils were also found in the northern section.
Deep sea mining is the extraction of minerals from the seabed of the deep sea. The main ores of commercial interest are polymetallic nodules , which are found at depths of 4–6 km (2.5–3.7 mi) primarily on the abyssal plain .
However, new fossils found in 2007 and 2008 showed that the "chain mail" of tommotiids formed the tube of a sessile animal; one tommotiid resembled phoronids, which are close relatives or a subgroup of brachiopods, while the other tommotiid bore two symmetrical plates that might be an early form of brachiopod valves.
A diverse array of ichnofossils have also been found at Joggins, including vertebrate trackways, invertebrate trace fossils, tunnel structures, rhizoliths, and possibly wood borings. [ 12 ] Fish coprolites are abundant in the limestone of the Joggins Formation, averaging lengths of 2–3 cm (0.79–1.18 in). [ 12 ]
In geochemistry, paleoclimatology and paleoceanography δ 18 O or delta-O-18 is a measure of the deviation in ratio of stable isotopes oxygen-18 (18 O) and oxygen-16 (16 O). It is commonly used as a measure of the temperature of precipitation, as a measure of groundwater/mineral interactions, and as an indicator of processes that show isotopic fractionation, like methanogenesis.