Conrad discontinuity[′kän‚rad dis‚känt·ən′ü·əd·ē]
(named after the Austrian geophysicist V. Conrad; 1876–1962), division surface between the “granitic” and “basaltic” layers of the continental part of the earth’s crust. In passing through the Conrad discontinuity the velocity of longitudinal seismic waves increases abruptly from approximately 6 to 6.5 km/sec. In a number of places there is no Conrad discontinuity, and the velocities of seismic waves increase gradually with depth. On the other hand, sometimes, several discontinuities are observed where velocities increase abruptly.