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Melting the Inner Earth
Today, the Earth’s density at any depth, z, is well known. Some values are given in column G of Table 30.1 Based on those values, the mass, acceleration due to gravity, polar moment of inertia, and gravitational potential energy are calculated in columns H–K for successive spherical shells. The potential energy of a shell of mass m and radius r is
where G is the gravitational constant, g is the acceleration due to gravity at r, and Mi is the mass inside the shell.
Preflood values of density (column B) can be estimated by the formula
density = a + bz + cz2 + dz3
where a = 2.840, b = 1.6362 × 10-3, c = 5.4000 × 10-8, and d = -1.1587 × 10-11. These coefficients were selected to satisfy the following constraints: the flood did not appreciably change the mass of the Earth,2 the preflood density at the Earth’s surface and center was what it is today (2.840 and 12.460 gm/cm3, respectively), pressure and, therefore, density increased smoothly with depth, and the polar moment of inertia allowed the Earth to rotate 360 times per year. (Endnotes 20–24, beginning on page 160, justify a 360-day year before the flood.) Other functional relationships between preflood density and depth that satisfied these same constraints would not greatly alter the following conclusions.
As explained on pages 142–165, during the flood, mass shifts within the Earth generated internal friction, heating, and melting. Melting, especially toward the center of the Earth where pressures (and thus frictional heating) were greatest, was followed by gravitational settling of the denser minerals and chemical elements. Rock that melted below the crossover depth contracted. [See pages 147–148.] This produced further mass shifts (faulting), frictional heating, melting, and gravitational settling. Most of the potential energy lost by the Earth—the difference in the sums of columns F and K—was converted to heat by gravitational settling.3
(2.489 × 1039 – 2.460 × 1039) = 29.0 × 1036 ergs
Once slippage began inside the earth, the potential energy lost by frictional melting eventually generated about 5 times more heat energy in the Earth’s core through gravitational settling.4 This created a runaway situation: more slippage and melting produced more heating by gravitational settling, which then produced even more slippage, etc. Within months, most of the inner earth melted. That melting, gravitational settling, and compression of magma in the outer core is shown by the sharp density discontinuity highlighted in yellow in Table 30 (column G) and by Earth’s extremely strong magnetic field. [See “The Origin of Earth’s Magnetic Field” on page 146 for an explanation.]
All this heat, released within months inside Earth, could provide almost 3 billion years’ worth of the present heat flux at the Earth’s surface (1.0 × 1028 ergs/year).
How does the heat released by gravitational settling (almost 29.0 × 1036 ergs) compare with the heat needed to form Earth’s present-day core? It partially depends on the initial temperatures of the denser particles inside the Earth before they fell toward the Earth’s center to become the inner and outer core. However, before gravitational settling could begin, those temperatures would have been raised to near the local melting temperatures. Particles that melted after they fell formed the liquid outer core; denser particles that did not melt or that solidified under the great pressure near the Earth’s center formed the solid inner core.
Anderson gives the following estimates for the thermal properties of the inner and outer core. (The masses for inner and outer core are derived from Table 30.)
| Property |
Inner Core |
Outer Core |
| Mass (gm) |
0.132 × 1027 |
1.831 × 1027 |
| Mean Melting Temperature (K) |
6,575 |
3,800 |
| Specific Heat (erg/gm/K) |
5 × 106 |
5 × 106 |
| Heat of Fusion (erg/gm) |
|
4 × 109 |
To form today’s inner core requires approximately
[5 × 106 × (6,575 – 3,800)] × 0.132 × 1027 = 1.832 × 1036 ergs
To form today’s outer core requires approximately
(4 × 109 ) × (1.831 × 10 27 ) = 7.324 × 1036 ergs
Therefore, the heat released by gravitational settling (almost 29.0 × 1036 ergs) exceeded that needed to form the Earth’s inner and outer core (9.156 × 1036 ergs). Temperatures quickly rose near the center of the Earth. Notice that the heat released by gravitational settling, if evenly distributed throughout the Earth, might melt the entire Earth, whose mass is 5.976 × 1027 grams.
29.0 × 1036 ergs > (~ 4 × 109 ) × (5.976 × 1027 ) ergs
Table 30 allows two other important conclusions. Evolutionists claim that the Earth formed by meteoritic bombardment, sometimes called gravitational accretion. If so, the 2.489 × 1039 ergs of potential energy lost by these meteoroids (sum of column K) would become heat after impact with the growing Earth. This is 86 times greater than the heat released by gravitational settling.