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The 'Mohorovičić' (IPA: [mɔhɔ'ɹɔvɪtʃɪtʃ]) 'discontinuity', usually referred to as the 'Moho', is the boundary between the Earth's crust and the mantle. The Moho serves to separate both oceanic crust and continental crust from underlying mantle. The Moho mostly lies entirely within the lithosphere; only beneath mid-ocean ridges does the Moho also define the mesosphere-asthenosphere boundary. The Mohorovičić discontinuity was first identified in 1909 by Andrija Mohorovičić, a Croatian seismologist, when he observed the abrupt increase in the velocity of earthquake waves (specifically P-waves) at this point. Ophiolites are sections of oceanic crust and possible mantle rock that have been obducted into the continental crust during plate collisions.
The interior Earth location of the Mohorovičić discontinuity ranges between about 5 km beneath the mid-ocean ridges to 30 to 50 km beneath typical continental crust. The depth to the Moho is approximately 75 km beneath the thickest continental crust, such as that of part of the Tibetan Plateau.
During the late 1950s and early 1960s, there was a proposal taken up in the executive committee of the National Science Foundation to drill a hole through the ocean floor to reach this boundary. However the operation, named ''Project Mohole'', never received sufficient support and the proposal was canceled by US Congress in 1967. This remains as an important scientific objective, which is being addressed by scientific drilling.

Contents

Moho in popular culture

See also

References

External links

Moho in popular culture

The Mohorovičić Discontinuity is mentioned in one particular computer game, an RTS called ''Total Annihilation.'' Players can build a "Moho Mine" in order to mine metal at or close to the Mohorovičić Discontinuity. Due to the size of the structure, the public being unfamiliar with the Mohorovičić Discontinuity, and an expansion structure called the "Moho Metal-Maker", "Moho" is misinterpreted as meaning "big."
The Mohorovičić Discontinuity is also mentioned in the novel ''Abduction'' by Robin Cook, in which a team of scientists are abducted by inhabitants of an underground civilization.
In the cartoon ''Inhumanoids'' the monster, D-Compose's kingdom of Skellweb lies within the Moho.
In ''Star Control 2'', one of the "ramblings" of the odd Mycon race is referring to the Deep Children as "Dwellers in the Mohorovichic." This is a reference to the fact that a "Deep Child" will burrow deep into the surface of a planet to begin de-terraforming.
''Deep Storm: A Novel'' by Lincoln Child details an expedition where a team of scientists attempts to drill through the ocean floor to the Mohorovičić Discontinuity.
In ''The Mohole Mystery'' by Hugh Walters lethal microbes and belligerent egg-shaped creatures inhabit the Mohorovičić Discontinuity when a manned rocket propelled capsule is sent down to investigate.
In the ''Mars trilogy'' by Kim Stanley Robinson, the colonizers of Mars dig deep "moholes" to allow outgassing from the planet's interior as a means to increase the atmospheric pressure - thus contributing to the terraforming of the planet.
Also, in ''Sid Meier's Alpha Centauri'' game, the Mohorovičić Discontinuity is mentioned with the technology advance "Industrial Automation." Another technology advance, "Ecological Engineering," allows terraforming units to dig "Thermal Boreholes," which are equivalent to moholes and which, in the game, produce both energy and minerals.

See also

★ Gutenberg Discontinuity

★ Lehmann discontinuity

★ Brittle-ductile transition zone

★ Kola Superdeep Borehole

References

★ Harris, P., 1972, 'The composition of the earth', in Gass, I.G., Smith, P.J., and Wilson, R.C.L. (eds), ''Understanding the Earth: A Reader in the Earth Sciences''. The Open University Press.

★ Schlumberger Oilfield Glossary
Douglas Dixon, P., 2000, "Beginners Guide To Geology" Chancellor Press.

External links

★ Hole Drilled to Bottom of Earth's Crust (2005)

★ Project Mohole, 1958-1966