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List Of Unsolved Problems In Geoscience
This list provides references to notable unsolved problems in geoscience. The early Earth and the solar system * Was there ever a collision of the Earth with another planet Theia, giving birth to our satellite? There is compelling evidence, such as measures of a shorter duration of the Earth's rotation and lunar month in the past, pointing to a Moon much closer to Earth during the early stages of the Solar System. * What is the long-term heat balance of Earth? How did its internal temperature decay since it formed by accretion of chondrites? How abundant are radiogenic elements in the interior? Did a " faint young Sun" ever warm a "snowball Earth"? Topography and environment *Can the now widely available topographic data be used to derive past tectonic and climatic conditions (in the multi-million year scale)? Do we know enough about the erosion and transport processes? Does the stochasticity of meteorological and tectonic events reflect in the landscape? How much has life contrib ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Unsolved Problems
List of unsolved problems may refer to several notable conjectures or open problems in various academic fields: Natural sciences, engineering and medicine * Unsolved problems in astronomy * Unsolved problems in biology * Unsolved problems in chemistry * Unsolved problems in engineering * Unsolved problems in geoscience * Unsolved problems in medicine * Unsolved problems in neuroscience * Unsolved problems in physics Mathematics, philosophy and information sciences * Unsolved problems in mathematics * Unsolved problems in statistics * Unsolved problems in computer science * Unsolved problems in philosophy * Unsolved problems in information theory Social sciences and languages * Unsolved problems in economics * Unsolved problems in fair division * Unsolved problems in linguistics See also * Cold case (unsolved crimes) * List of ciphertexts * List of NP-complete problems * List of PSPACE-complete problems * List of paradoxes * List of undecidable problems * List of unsolv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skyquake
A skyquake is a phenomenon where a loud booming sound is reported to originate from the sky. The sound may cause noticeable vibration in a building or across a particular area. Those who experience skyquakes typically do not have a clear explanation for what caused them and they are perceived as mysterious. They have been heard in several locations around the world, including the banks of the river Ganges, Marwadi/Marawadi (मरवड़ी/मराड़ी) village in Himachal Pradesh, the East Coast and inland Finger Lakes of the United States, the city of Hudson, Wisconsin, the Magic Valley in South Central Idaho of the United States, Colombia, Southern Canada, as well as areas of the North Sea, Japan, Finland, Australia, Italy, Drogheda, Bettystown, Slane, Dundalk, Ireland, England, Pune, Ambala, The Netherlands, Norway, Bengaluru, Tierra del Fuego Argentina, United Kingdom, Jakarta and West Java (), Brazil, Uruguay, Tampico, Mexico on , Central Java on (), Bandung of West ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chandler Wobble
The Chandler wobble or Chandler variation of latitude is a small deviation in the Earth's axis of rotation relative to the solid earth, which was discovered by and named after American astronomer Seth Carlo Chandler in 1891. It amounts to change of about in the point at which the axis intersects the Earth's surface and has a period of 433 days. This wobble, which is an astronomical nutation, combines with another wobble with a period of one year, so that the total polar motion varies with a period of about 7 years. The Chandler wobble is an example of the kind of motion that can occur for a freely rotating object that is not a sphere; this is called a free nutation. Somewhat confusingly, the direction of the Earth's rotation axis relative to the stars also varies with different periods, and these motions—caused by the tidal forces of the Moon and Sun—are also called nutations, except for the slowest, which are precessions of the equinoxes. Predictions The existence of E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Core–mantle Boundary
The core–mantle boundary (CMB) of Earth lies between the planet's silicate mantle and its liquid iron-nickel outer core. This boundary is located at approximately 2,891 km (1,796 miles) depth beneath Earth's surface. The boundary is observed via the discontinuity in seismic wave velocities at that depth due to the differences between the acoustic impedances of the solid mantle and the molten outer core. P-wave velocities are much slower in the outer core than in the deep mantle while S-waves do not exist at all in the liquid portion of the core. Recent evidence suggests a distinct boundary layer directly above the CMB possibly made of a novel phase of the basic perovskite mineralogy of the deep mantle named post-perovskite. Seismic tomography studies have shown significant irregularities within the boundary zone and appear to be dominated by the African and Pacific Large Low-Shear-Velocity Provinces (LLSVP). The uppermost section of the outer core is thought to be about 500 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polar Drift
Polar drift is a geological phenomenon caused by variations in the flow of molten iron in Earth's outer core, resulting in changes in the orientation of Earth's magnetic field, and hence the position of the magnetic north- and south poles. The North Magnetic Pole is approximately from the geographic north pole. The pole drifts considerably each day, and since 2007 it moves about per year as a result of this phenomenon. The South Magnetic Pole is constantly shifting due to changes in the Earth's magnetic field. it was calculated to lie at , placing it off the coast of Antarctica, between Adelie Land and Wilkes Land. In 2015, it lay at (est). That point lies outside the Antarctic Circle and it is moving northwest by about per year. Its current distance from the actual Geographic South Pole is approximately . The nearest permanent science station is Dumont d'Urville Station. Wilkes Land contains a large gravitational mass concentration. ; North Magnetic Pole : 1900: : 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transition Zone (Earth)
The transition zone is part of the Earth's mantle, and is located between the lower mantle and the upper mantle, between a depth of 410 and 660 km (250 to 400 mi). The Earth's mantle, including the transition zone, consists primarily of peridotite, an ultramafic igneous rock. The mantle was divided into the upper mantle, transition zone, and lower mantle as a result of sudden seismic-velocity discontinuities at depths of 410 and 660 km (250 to 400 mi). This is thought to occur as a result of rearrangement of grains in olivine (which constitutes a large portion of peridotite) at a depth of 410 km, to form a denser crystal structure as a result of the increase in pressure with increasing depth. Below a depth of 660 km, evidence suggests due to pressure changes ringwoodite minerals change into two new denser phases, bridgmanite and periclase. This can be seen using body waves from earthquakes, which are converted, reflected or refracted at the boundar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supervolcano
A supervolcano is a volcano that has had an eruption with a Volcanic Explosivity Index (VEI) of 8, the largest recorded value on the index. This means the volume of deposits for such an eruption is greater than 1,000 cubic kilometers (240 cubic miles). Supervolcanoes occur when magma in the mantle rises into the crust but is unable to break through it. Pressure builds in a large and growing magma pool until the crust is unable to contain the pressure and ruptures. This can occur at hotspots (for example, Yellowstone Caldera) or at subduction zones (for example, Toba). Large-volume supervolcanic eruptions are also often associated with large igneous provinces, which can cover huge areas with lava and volcanic ash. These can cause long-lasting climate change (such as the triggering of a small ice age) and threaten species with extinction. The Oruanui eruption of New Zealand's Taupō Volcano (about 26,500 years ago) was the world's most recent VEI-8 eruption. Terminology ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hessdalen Lights
The Hessdalen lights are unidentified lights observed in a stretch of the Hessdalen valley in rural central Norway. Background The Hessdalen lights are of unknown origin. They appear both by day and by night, and seem to float through and above the valley. They are usually bright white, yellow or red and can appear above and below the horizon. The duration of the phenomenon may be a few seconds to well over an hour. Sometimes the lights move with enormous speed; at other times they seem to sway slowly back and forth. On yet other occasions, they hover in mid‑air. Unusual lights have been reported in the region since at least the 1930s. Especially high activity occurred between December 1981 and mid-1984, during which the lights were observed 15–20 times per week, attracting many overnight tourists. , the number of observations had dwindled, with only 10 to 20 sightings yearly. Since 1983, "Project Hessdalen" initiated by UFO-Norge and UFO-Sverige have attempted to investiga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geoscience
Earth science or geoscience includes all fields of natural science related to the planet Earth. This is a branch of science dealing with the physical, chemical, and biological complex constitutions and synergistic linkages of Earth's four spheres, namely biosphere, hydrosphere, atmosphere, and geosphere. Earth science can be considered to be a branch of planetary science, but with a much older history. Earth science encompasses four main branches of study, the lithosphere, the hydrosphere, the atmosphere, and the biosphere, each of which is further broken down into more specialized fields. There are both reductionist and holistic approaches to Earth sciences. It is also the study of Earth and its neighbors in space. Some Earth scientists use their knowledge of the planet to locate and develop energy and mineral resources. Others study the impact of human activity on Earth's environment, and design methods to protect the planet. Some use their knowledge about Earth processes such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neogene
The Neogene ( ), informally Upper Tertiary or Late Tertiary, is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago ( Mya) to the beginning of the present Quaternary Period Mya. The Neogene is sub-divided into two epochs, the earlier Miocene and the later Pliocene. Some geologists assert that the Neogene cannot be clearly delineated from the modern geological period, the Quaternary. The term "Neogene" was coined in 1853 by the Austrian palaeontologist Moritz Hörnes (1815–1868). During this period, mammals and birds continued to evolve into modern forms, while other groups of life remained relatively unchanged. The first humans (''Homo habilis'') appeared in Africa near the end of the period. Some continental movements took place, the most significant event being the connection of North and South America at the Isthmus of Panama, late in the Pliocene. This cut off the warm ocean currents from the Pacific to th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Retrogressive Erosion
Headward erosion is erosion at the origin of a stream channel, which causes the origin to move back away from the direction of the stream flow, lengthening the stream channel.Essentials of Geology, 3rd Ed, Stephen Marshak It can also refer to widening of a canyon by erosion along its very top edge, when sheets of water first enter the canyon from a more roughly planar surface above it, such as at Canyonlands National Park in Utah. When sheets of water on a roughly planar surface first enter a depression in it, this erodes the top edge of the depression. The stream is forced to grow longer at the very top of the stream, which moves its origin back, or causes the canyon formed by the stream to grow wider as the process repeats. Widening of the canyon by erosion inside the canyon, below the canyon side top edge, or origin or the stream, such as erosion caused by the streamflow inside it, is not called headward erosion. Headward erosion is a fluvial process of erosion that lengthe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
