<P> The average density of Earth is 7000551499999999999 ♠ 5.515 g / cm . Because the average density of surface material is only around 7000300000000000000 ♠ 3.0 g / cm , we must conclude that denser materials exist within Earth 's core . This result has been known since the Schiehallion experiment , performed in the 1770s . Charles Hutton in his 1778 report concluded that the mean density of the Earth must be about 9 5 ( \ displaystyle ( \ tfrac ( 9 ) ( 5 ) ) ) that of surface rock , concluding that the interior of the Earth must be metallic . Hutton estimated this metallic portion to occupy some 65 % of the diameter of the Earth . Hutton 's estimate on the mean density of the Earth was still about 20 % too low , at 7000450000000000000 ♠ 4.5 g / cm Henry Cavendish in his torsion balance experiment of 1798 found a value of 7000545000000000000 ♠ 5.45 g / cm , within 1 % of the modern value . Seismic measurements show that the core is divided into two parts , a `` solid '' inner core with a radius of ≈ 1,220 km and a liquid outer core extending beyond it to a radius of ≈ 3,400 km . The densities are between 9,900 and 12,200 kg / m in the outer core and 12,600 -- 13,000 kg / m in the inner core . </P>
<P> The average density of Earth is 7000551499999999999 ♠ 5.515 g / cm . Because the average density of surface material is only around 7000300000000000000 ♠ 3.0 g / cm , we must conclude that denser materials exist within Earth 's core . This result has been known since the Schiehallion experiment , performed in the 1770s . Charles Hutton in his 1778 report concluded that the mean density of the Earth must be about 9 5 ( \ displaystyle ( \ tfrac ( 9 ) ( 5 ) ) ) that of surface rock , concluding that the interior of the Earth must be metallic . Hutton estimated this metallic portion to occupy some 65 % of the diameter of the Earth . Hutton 's estimate on the mean density of the Earth was still about 20 % too low , at 7000450000000000000 ♠ 4.5 g / cm Henry Cavendish in his torsion balance experiment of 1798 found a value of 7000545000000000000 ♠ 5.45 g / cm , within 1 % of the modern value . Seismic measurements show that the core is divided into two parts , a `` solid '' inner core with a radius of ≈ 1,220 km and a liquid outer core extending beyond it to a radius of ≈ 3,400 km . The densities are between 9,900 and 12,200 kg / m in the outer core and 12,600 -- 13,000 kg / m in the inner core . </P>
in what part of the earths internal structure can rocks melt
in what part of the earths internal structure can rocks melt
outer core
outer core