(ËlÉk tÉrn) n. 1. a reading desk in a church from which the Bible lessons are read during the service. 2. a stand with a slanted top, used to hold a book, speech, etc., at the proper height for a standing reader or speaker.
How a Diamond is Formed. In order for diamond to form there must be an available source of carbon and relatively narrow ranges of temperates and pressures must align. This happens around 100 miles below the crust. Once crystalized the diamonds must be rapidly transported to the surface without undergoing substantial change.
(See Location 2 in the diagrams above and at right.) Diamond formation in a subducting plate might occur as little as 50 miles (80 kilometers) below the surface and at temperatures as low as 390 degrees Fahrenheit (200 degrees Centigrade) (1).