<P> The inner core was discovered in 1936 by Inge Lehmann and is generally believed to be composed primarily of iron and some nickel . Since this layer is able to transmit shear waves ( transverse seismic waves ) , it must be solid . Experimental evidence has at times been critical of crystal models of the core . Other experimental studies show a discrepancy under high pressure : diamond anvil ( static ) studies at core pressures yield melting temperatures that are approximately 2000 K below those from shock laser ( dynamic ) studies . The laser studies create plasma , and the results are suggestive that constraining inner core conditions will depend on whether the inner core is a solid or is a plasma with the density of a solid . This is an area of active research . </P>
<P> The inner core was discovered in 1936 by Inge Lehmann and is generally believed to be composed primarily of iron and some nickel . Since this layer is able to transmit shear waves ( transverse seismic waves ) , it must be solid . Experimental evidence has at times been critical of crystal models of the core . Other experimental studies show a discrepancy under high pressure : diamond anvil ( static ) studies at core pressures yield melting temperatures that are approximately 2000 K below those from shock laser ( dynamic ) studies . The laser studies create plasma , and the results are suggestive that constraining inner core conditions will depend on whether the inner core is a solid or is a plasma with the density of a solid . This is an area of active research . </P>
when was the structure of the earth discovered
when was the structure of the earth discovered
1936
1936