Structure of the Earth discontinuity (a second order discontinuity). The uppermost mantle together with the crust constitutes the lithosphere. The crust-mantle boundary occurs as two physically different events. First, there is a discontinuity in the seismic velocity, which is most commonly known as the Mohorovičić discontinuity or Moho. The cause of the Moho is thought to be a change in rock composition from rocks containing plagioclase feldspar (above) to rocks that contain no feldspars (below). Second, in oceanic crust, there is a chemical discontinuity between ultramafic cumulates and tectonized harzburgites, which has been observed from deep parts of the oceanic crust that have been
The Cyborg from Earth The Cyborg from Earth The Cyborg from Earth is a 1998 science fiction novel by Charles Sheffield. It is the fourth in a series of unrelated stories, published by Tor Books in their Jupiter line. The novel starts in a future dystopian Earth where the upper class lives a life of privilege, while most others live in the "pool", an endless crowd of unemployable youths depending on government assistance or crime for survival. The book is told from the perspective of the main character, Jefferson Kopal, a young member of an immensely wealthy and powerful spaceship building family founded by