1857-1936

Croatian geologist who discovered Earth's crust-mantle boundary—the Mohorovicic discontinuity. Mohorovicic's study of seismic records from a 1909 earthquake revealed two distinct sets of waves. This indicated that the seismic waves had changed velocity, which Mohorovicic attributed to transmission through two layers of different density. He identified the boundary between the two layers as a sharp discontinuity, now known to vary from 10 km (6.2 miles) under the oceans to as much as 50 km (31 miles) under continents.