on April 9, 2022
Why are some continental margins active and others passive?
GeologyThe distinction between active and passive margins refers to whether a crustal boundary between oceanic lithosphere and continental lithosphere is a plate boundary. Active margins are found on the edge of a continent where subduction occurs. Why are continental margins passive? The continents moved away from one another as parts of different tectonic plates. The
on April 9, 2022
What is conservative margin?
GeologyA conservative (passive or transform as it is also known) plate margin involves two tectonic plates sliding past each other. The plates do not pass each other smoothly. Friction causes them to get stuck. Over time pressure builds up until the friction is overcome which results in the plates slipping. What does conservative margin mean?
on April 9, 2022
Who first presented the periglacial cycle of erosion?
GeologyIn 1950 L.C Peltier put forward the concept of a periglacial cycle of erosion. Who propounded glacial cycle of erosion? William Morris Davis However the immediate influences of William Morris Davis, the creator of the cycle of erosion model, were 19th century American explorers. Who was the first to give the idea of cycle of
on April 9, 2022
Why is sequence stratigraphy important?
GeologySequence stratigraphy can be used to develop more accurate surfaces for mapping and correlating facies; predict reservoir, source and sealing facies; identify stratigraphic traps; and project reservoir trends into areas with limited data. Why principles of stratigraphy is important? stratigraphy, scientific discipline concerned with the description of rock successions and their interpretation in terms of
on April 9, 2022
What is a reverse earthquake?
GeologyIf the rock mass above an inclined fault moves down, the fault is termed normal, whereas if the rock above the fault moves up, the fault is termed reverse. What is the meaning of reverse in earthquake? How does a reverse fault move? In a reverse fault, the block above the fault moves up relative
on April 9, 2022
Why are oceanic plates denser than Continental?
GeologyWhy is the oceanic crust more dense? Oceanic crust is denser because it generally melts to a higher fraction than continental crust. When rocks melt to 20–30% like they do at mid-ocean ridges, the result is more dense than when rocks melt to form continental plates, which is typically 1–5%. Why is continental crust less
on April 9, 2022
What is the density of the mantle?
Geology3“>4.5 g/cm34.5 g/cm3, and temperatures in the range of 1000-1500 oC. The uppermost layer of the mantle is more rigid, while the deeper regions are fluid, and it is the motion of fluid materials in the mantle that is responsible for plate tectonics (see section 4.3). What is the average density of the lower mantle?
on April 9, 2022
What are the different eras in the geologic time scale?
GeologyThe Precambrian, Paleozoic, Mesozoic, and Cenozoic Eras The Geologic Time Scale is the history of the Earth broken down into four spans of time marked by various events, such as the emergence of certain species, their evolution, and their extinction, that help distinguish one era from another. What are the 6 eras on the geologic
on April 9, 2022
What is a sinkhole and how is it formed?
GeologySinkholes are formed when the land surface above collapses or sinks into the cavities or when surface material is carried downward into the voids. Drought, along with resulting high groundwater withdrawals, can make conditions favorable for sinkholes to form. How deep is a sinkhole? Sinkholes can be anywhere from a few feet wide and deep,
on April 9, 2022
Is sandstone a crystalline?
GeologyIs sandstone a crystalline rock? Feldspathic sandstones are derived from granitic-type, primary crystalline, rocks. If the sandstone is dominantly plagioclase, then it is igneous in origin. … This type of rock contains less than 90% quartz grains and more unstable rock fragments than feldspars. Is sandstone clastic or crystalline? Sandstone is a clastic sedimentary rock