Latest Petrology Stories
One team of researchers has uncovered the factors that determine the frequency and magnitude of volcanic activity, while another has identified the triggers for the rare and explosive eruptions experienced by supervolcanoes, according to studies currently appearing in the advanced online edition of the journal Nature Geoscience.
GSA Bulletin articles posted online ahead of print on 6 and 13 December 2013 cover earthquake hazards of the Santa Barbara suburban area; apatite and the skeletons of early animals; the peculiar geological features of Faial (Azores, Portugal); the nature of Mount Rainier; the origin of Pearya terrane, Canada; a re-interpretation of the Chilhowee Group of the Appalachian Blue Ridge; and more.
A University of Houston (UH) geoscientist and his colleagues are revealing new discoveries about the Earth's development, following a major international expedition that recovered the first-ever drill core from the lower crust of the Pacific Ocean.
By analyzing basalt, a substance formed from cooling lava, a team of European scientists have gained new insight into how the Earth’s core, crust and atmosphere formed, as well as how volcanic activity originated.
An archaeologist at the University of Sheffield has found evidence that, contrary to a widely held theory, ancient Syrians made their stone tools locally instead of importing finished tools from Turkey.
a new study indicated that bizarre pillars of basalt in Iceland's Skaelingar valley were formed by a very slow lava flow oozing from volcanoes and interacting with water.
Scientists writing in the journal Nature Geoscience say that a similar process to that which allows water to yank oils from ground coffee in order to make a cup of joe in the morning, could be how the Earth's core formed.
A recent study changes the understanding of how the Hawaiian Islands formed. Scientists have determined that it is the eruptions of lava on the surface, extrusion, which grow Hawaiian volcanoes, rather than internal emplacement of magma, as was previously thought.
A powerful earthquake that struck the southwestern province of Baluchistan, Pakistan Tuesday afternoon, killing hundreds of people, has given rise to a new island off the coast of the country's Gwadar Port.
Obsidian is a naturally occurring volcanic glass with a smooth, hard surface. Obsidian is far sharper than a surgical scalpel when fractured, making it a highly desirable raw material for crafting stone tools for almost all of human history.
Chaitén is a volcanic caldera that is located in southern Chile that reaches an elevation of 3,681 feet. It is thought that this volcano once held a rhyolite obsidian lava dome that reached 3,156 in height, but this was destroyed after its most recent eruption in 2008. In the past, this volcano has released grey obsidian, which was used by pre-Columbian cultures to make many objects, some of which have been found 250 miles away from the volcano. Chaitén experienced the beginning of a new...
Biotite is a common phyllosilicate mineral that contains potassium, magnesium, iron and aluminium. It is sometimes called "iron mica" and is found in granitic rocks, gneisses, and schists. Like other mica minerals, biotite has a highly perfect basal cleavage, its flexible sheets easily flaking off. It has a hardness of 2.5 - 3, a specific gravity of 2.7 - 3.1, is colored greenish to brown or black, and can be transparent to opaque. Biotite is occasionally found in large sheets, especially in...
Chert is a fine-grained silica-rich cryptocrystalline sedimentary rock that may contain small fossils. It varies greatly in color from white to black, but most often manifests as gray, brown, grayish brown and light green to rusty red; its color is an expression of trace elements present in the rock, and both red and green are most often related to traces of iron (in its oxidized and reduced forms respectively). It outcrops as nodules in limestone, chalk, and dolostone formations as a...
Chromite, iron magnesium chromium oxide: (Fe,Mg)Cr2O4, is an oxide mineral belonging to the spinel group. Magnesium is always present in variable amounts, also aluminium and iron substitute for chromium. Chromite is found in peridotite and other layered ultramafic intrusive rocks and also found in metamorphic rocks such as serpentinites. Ore deposites of chromite form as early magmatic differentiates. It is commonly associated with olivine, magnetite, serpentine, and corundum. Chromite is...
In geology, a conglomerate is a rock consisting of other stones that have been cemented together. Conglomerates are sedimentary rocks consisting of subangular clasts and are thus differentiated from breccias, which consist of angular clasts. Both conglomerates and breccias are characterized by clasts larger than sand (>2 mm). There are two varieties of conglomerate, defined by texture: paraconglomerates and orthoconglomerates. Paraconglomerates are one of two varieties of conglomerate...
- totally perplexed and mixed up.
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