on April 16, 2022
Is greywacke a metamorphic rock?
GeologyGraywacke sandstone is a sedimentary rock that is made up mosttly of sand-size grains that were rapidly deposited very near the source rock grom which they were weathered. What type of rock is greywacke? Graywacke sandstone is a sedimentary rock that is made up mostly of sand-size grains that were rapidly deposited very near the
on April 16, 2022
Who is the most famous seismologist?
GeologyCharles F. Richter, in full Charles Francis Richter, (born April 26, 1900, near Hamilton, Ohio, U.S.—died September 30, 1985, Pasadena, California), American physicist and seismologist who developed the Richter scale for measuring earthquake magnitude. Who is the best seismologist in the world? WILLIAM ELLSWORTH, professor of geophysics at Stanford Earth, has won the Seismological Society
on April 16, 2022
How was the North American continent formed?
GeologyThe continental fragments constituting interior North America coalesced between about 2.0 and 1.8 billion years ago. The amalgamation began about 1.97 billion years ago, when the Slave province collided obliquely with the western Churchill province. Where is the North American Craton? One of those original continents is the North American craton, located mostly in the
on April 16, 2022
How much of Earth’s history took place during the Precambrian eon?
Geology90%almost 90% of the entire history of the Earth. It has been divided into three eras: the Hadean, the Archean and the Proterozoic. The Precambrian Era comprises all of geologic time prior to 600 million years ago. What percent of Earth’s history is Precambrian? 88 percent Precambrian (Informal—4.6 billion years ago to 541 million years
on April 16, 2022
What is block cave mining?
GeologyTouted as the deep mining method of the future, block caving is an underground mass-mining method that allows for the bulk extraction of large, relatively lower-grade ore deposits that are vertical in orientation. What does block caving mean? Definition of block-caving : a mining in which sections of a large ore body are undercut by
on April 16, 2022
What are the time divisions that are used for the geologic time scale and what determines how they are divided?
GeologyIn the Geologic Time Scale, time is generally divided on the basis of the earth’s biotic composition, with the Phanerozoic Eon (i.e. the Paleozoic, Mesozoic and Cenozoic Eras) representing the period of Earth’s history with advanced life forms, and the Pre Cambrian (or Proterozoic and Hadean Eras) representing the … What are the divisions of
on April 16, 2022
What is mafic magma?
GeologyDescribes magma that contains lower amounts of silica and is generally less viscous and less gas-rich than silicic magma. Tends to erupt effusively, as lava flows. Includes andesites (57-63 percent SiO2), basaltic andesites (53-57 percent SiO2), and basalts (47-53 percent SiO2). What are the characteristics of mafic magma? Mafic magmas are low in silica and
on April 16, 2022
Can you really dig to China?
GeologyYou can technically dig through the Earth to get to China, but it’s more challenging than it sounds. If you want to dig to China, you’d actually need to start your journey in Chile or Argentina — not the US. Can you dig straight down to China? To dig to China, you’d need to start
on April 16, 2022
What is a medial moraine?
GeologyMedial moraines form where two tributary glaciers come together. They are generally surficial features on the ice and often consist of rock that has fallen from a rockwall where the glaciers converge. Because they are thin, surficial features, medial moraines are rarely preserved after the ice retreats. Where are medial moraines? A medial moraine is
on April 16, 2022
What is a vitreous luster?
GeologyVitreous lustre Vitreous minerals have the lustre of glass. (The term is derived from the Latin for glass, vitrum.) This type of lustre is one of the most commonly seen, and occurs in transparent or translucent minerals with relatively low refractive indices. What does vitreous luster look like? Specimens that have a vitreous luster have