EVERYDAY SCIENCE

Detailed explanation-1: -The second of Oldham’s great findings was the discovery of Earth’s core. He studied the propagation of seismic wave paths from Earthquakes originating all around the world and found that certain waves were refracted and changed speeds as they pass through the Earth’s interior while others were not.

Detailed explanation-2: -Richard Dixon Oldham, (born July 31, 1858, Dublin, Ire.-died July 15, 1936, Llandrindod, Wales), British geologist and seismologist who discovered evidence for the existence of the Earth’s core.

Detailed explanation-3: -Earth was discovered to have a solid inner core distinct from its molten outer core in 1936, by the Danish seismologist Inge Lehmann, who deduced its presence by studying seismograms from earthquakes in New Zealand.

Detailed explanation-4: -However, Oldham was the first who discovered and published about the shadow effect of the Earth’s core due to lower seismic velocities. Together with his work on seismic phase types, Oldham is one of the pioneers for the application of seismic‐wave phenomena to investigate the structure of the Earth’s interior.

Detailed explanation-5: -Inge Lehmann (1888-1993), discoverer of the Earth’s inner core.