1888-1993

Danish seismologist who was awarded the 1971 American Geophysical Union's William Bowie Medal for "outstanding contributions to fundamental geophysics and unselfish cooperation in research." Lehmann's seismic wave observations led her to conclude in 1936 that Earth has a solid inner-core surrounded by a liquid outer-core. She calculated the inner-core radius to be 1,400 km (870 mi) and noted that seismic waves were reflected at its outer-core boundary. This boundary has been named the "Lehmann discontinuity" in her honor.