Mantle plumes are a geological phenomenon originally proposed by W. Jason Morgan in 1971. He described them as hot upwellings of relatively primordial material which rise from the deep mantle of the Earth and feed geological hotspots on the surface such as Iceland and Hawaii. Such plumes rise because of thermal buoyancy and must originate at a thermal boundary layer. The only such layer known to exist in the deep mantle is the core-mantle boundary (D"), and thus Morgan-type plumes are generally assumed to rise from this layer. Geology (from Greek γη- (ge-, the earth) and λογος (logos, word, reason)) is the science and study of the Earth, its composition, structure, physical properties, history, and the processes that shape it. ... 1971 is a common year starting on Friday (click for link to calendar). ... The mantle is the layer in the structure of the Earth that lies directly under the Earths crust. ... In geology, a hotspot is a location on the Earths surface that has experienced active vulcanism for a long period of time. ... State nickname: The Aloha State Other U.S. States Capital Honolulu Largest city Honolulu Governor Linda Lingle Official languages Hawaiian and English Area 28,337 km² (43rd)  - Land 16,649 km²  - Water 11,672 km² (41. ... Convection is the transfer of heat by the motion of or within a fluid. ... The boundary layer is the layer of fluid in the immediate vicinity of a bounding surface. ... The planetary core consists of the innermost layers of a planet. ...

This theory has been popular for over 30 years. However, irrefutable evidence for such plumes has still not been confirmed, and contrary, or unexpected observations are often reported. On the other hand, low-wave-speed seismic anomalies with different shapes, e.g., shallow, or very wide bodies have been found. Such observations led to diversification of the range of features that scientists call plumes. A clear, widely accepted definition of a plume thus does not currently exist, and the word plume is often used by different scientists to mean different things. Furthermore, it has become essentially impossible to disprove the plume hypothesis because the term plume has become vague and all-embracing. A vigorous global debate has developed concerning whether plumes exist at all. The word theory has a number distinct meanings depending on the context. ... Seismology (from the Greek seismos = earthquake and logos = word) is the scientific study of earthquakes and the movement of waves through the Earth. ... Falsification is the act of disproving a theory. ... A hypothesis (= assumption in ancient Greek) is a proposed explanation for a phenomenon. ...

In a 2004 paper, Don L. Anderson and James H. Natland write: 2004 is a leap year starting on Thursday of the Gregorian calendar. ...

"Unfortunately, the terms hotspot and plume have become confused. In recent literature the terms are used interchangeably. A plume is a hypothetical mantle feature. A hotspot is a region of magmatism or elevation that has been deemed to be anomalous in some respect because of its volume or location. In the plume hypothesis, a hotspot is the surface manifestation of a plume, but the concepts are different; one is the presumed effect, and the other is the cause."

Major Ore Deposits as a result of Mantle Plume Activity: This article is about the type of rock. ... Elevation has several related meanings: Geography The elevation of a geographic location is its height above mean sea level (or possibly some other fixed point). ...

• Nickel Deposits
• Copper Deposits
• Diamond Deposits
• Sulfide Deposits
• Gold Deposits (to a lesser extent)

General Name, Symbol, Number nickel, Ni, 28 Chemical series transition metals Group, Period, Block 10 , 4, d Density, Hardness 8908 kg/m³, 4. ... General Name, Symbol, Number copper, Cu, 29 Chemical series transition metals Group, Period, Block 11 , 4, d Density, Hardness 8920 kg/m3, 3. ... A scattering of round-brilliant cut diamonds shows off the many reflecting facets. ... In chemistry, a sulfide (sulphide in British and Canadian English) is a combination of sulfur with an oxidation number of -2, with another chemical element or a radical thereof. ... General Name, Symbol, Number Gold, Au, 79 Chemical series transition metals Group, Period, Block 11 (IB), 6, d Density, Hardness 19. ...

References

• Anderson, Don L. & Natland, James H. (June 23, 2004). A brief history of the plume hypothesis and its competitors: Concept and controversy (http://www.mantleplumes.org/Penrose/BookChapterPDFs/AndersonHistory_Revised.pdf). Retrieved Sep. 15, 2004.

External links

• MantlePlumes.org (http://www.mantleplumes.org/)