IBRI Research Report No. 47 (1999)
Meteorites and the Maker's Mortar for Earth and Ocean
Matt L. McCullough
Copyright © 1999 by Matt L. McCullough. All rights
|There is widespread scientific agreement (fitting Genesis 1:2) that the early Earth was covered by water. Some meteorites contain significant amounts of water, especially carbonaceous chondrites. When stony meteorites are subjected to extreme shock pressures and heating as would occur on impact, they give up their water and other volatiles. As a result the early Earth, which formed from an accretion process involving the impact of meteors, acquired a hydrous atmosphere and magma ocean. As the earth cooled off, the water condensed to form an ocean. Ultimately, this water was used in the formation of the earth beneath our feet.|
|Although the author is in agreement with the doctrinal statement of IBRI, it does not follow that all of the viewpoints espoused in this paper represent official positions of IBRI. Since one of the purposes of the IBRI report series is to serve as a preprint forum, it is possible that the author has revised some aspects of this work since it was first written.|
Although the world's attention has recently been captured by stunning pictures of comet Hale-Bopp and by the discovery of microbe-like structures within a Martian meteorite, recent Hollywood films suggest our fascination with such objects comes mostly from the fear that they might destroy us. However, the real "impact" these objects have had in our lives __ as part of God's work in constructing the Earth and its life-supporting ocean - has tended to escape our notice.
According to Genesis 1:2, the Earth in its infancy was covered by water:
"darkness was over the surface to the deep; and the spirit of God was moving
over the surface of the waters." Likewise, there is widespread scientific
agreement that the newborn Earth was indeed covered by water (and darkly
so). Planetary scientists generally believe that the Earth formed through
an accretion process from a rotating disk of gas and dust around our Sun
which gravitationally collapsed. Dust particles which condensed within
this cloud began to form larger meteoritic-type bodies, called planetesimals,
through cohesion and collisional accumulation. Continued collision and
coalescence of these bodies produced embryonic planets, which in turn grew
into the Earth and the other planets we see today.
Evidence that Earth was essentially hammered together piece-by-piece
through such a process includes the clearly-cratered surfaces of the Moon,
Mars and Mercury, and the various axial tilts and chemical compositions
found among the planets.1 Fortunately, the
continuation of this process on a small scale has allowed us to examine
the very mortar of our planet - meteorites. Scientists have discovered
that a careful mixing and pounding together of this mortar not only produced
the Earth, but also our oceans and atmosphere. After all, "This is what
God the Lord says __ he who created the heavens and stretched
them out, who pounded out2 the earth
and all that comes out of it" (Isaiah 42:5).
Composition and Alteration of Meteorites
Compositional analyses of meteorites have shown that some of them contain
significant amounts of water, especially carbonaceous chondrites, a type
of stony meteorite. Type 1 carbonaceous chondrites (commonly known as CI
chondrites) may contain up to 20% of H2O in the form of hydrous
minerals known as phyllosilicates.3-4 Because
these chondrites have elemental abundances similar to those of the Sun,
they are recognized as the most primitive type of material we have surviving
from the early solar system.5 Carbonaceous
chondrites also have atomic weight compositions (i.e., ratios of the various
isotopes) of carbon, nitrogen, hydrogen, and inert gases similar to that
of the outer shell or crust of the Earth.6
Study of the rock-forming elemental abundances, water and other volatile
contents of these meteorites (along with other chondritic types) can also
be related closely to the bulk composition of the Earth.7-9
Evidence that the water in meteorites we recover is indigenous, rather
than due to terrestrial contamination, includes measurements of their isotopes
plus abundant signs of their early aqueous alteration. The presence in
these meteorites of water-bearing silicate mineral veins, and veins of
water-precipitated minerals such as sulphates and carbonates, indicate
that liquid water once circulated through the meteorite's parent body.10-11
Measurements of the ratios of magnesium and chromium isotopes within carbonate
veins in CI chondrites have also shown that this aqueous activity sometimes
occurred very early, just after the first solids formed from the solar
nebula.12 Minerals within the meteorites may
be further altered hydrothermally by shock deformation from impact.13-14
Unfortunately impact effects, melting, and subsequent alteration on
Earth (or even high within our atmosphere) limit some of the usefulness
of this information, making it difficult to determine whether a meteorite
has come from a comet or from some other body such as an asteroid. Consequently,
scientists are looking forward to the return of NASA's Stardust
spacecraft, which in 2006 is expected to bring back from the comet Wilt-2
some pristine nebular dust believed to be of chondritic composition.15
Formation of the Early Atmosphere and a World Ocean
However, this alteration of meteoritic material has benefitted us as well. Experiments in which stony meteorites have been subjected to such extreme shock pressures or heating as would occur from their impact with Earth demonstrate that they would have lost their water and other volatiles such as CO2. This dehydration or outgassing of the parent rock begins to occur when the impact velocity exceeds about 2 km/sec, with complete dehydration for speeds greater than 4 km/sec.16-18 Planetesimals falling onto objects like the Earth would have achieved velocities sufficient to totally devolatize the incident bodies by the time the Earth had grown to about 27% of its present size.19 Consequently, a primordial atmosphere composed mostly of water vapor and lesser amounts of CO2 was generated.
Studies which model the more complex effects of the shock devolatization of chondrites have shown that large impacts on the one hand, or the blanketing effect of an impact-induced atmosphere on the other, can increase the surface temperature of the accreting Earth to the point where a magma ocean is formed.20-23 Any surviving volatiles in the planetesimals would then dissolve in the magma. The magma layer would allow iron and silicate separation to occur, with the iron subsequently sinking to form the Earth's core. The magma ocean in turn controls the amount of H2O in the atmosphere since water can easily be dissolved into the silica-rich magma or degassed from it, depending on the atmospheric pressure. This has profound implications. Even if the Earth's atmosphere was once lost into space from a large impact during the accretion process, water vapor could be outgassed from the remaining magma and replenish it.24
As the accretion rate slowed and the radius of the Earth approached
its present value, the interior heat of the Earth eventually decreased,
and solar radiation became the main heat source for the atmosphere. Since
the solar radiation could not readily penetrate the dense, opaque atmosphere,
the lower atmosphere began to cool and the water in the atmosphere condensed
into a liquid.25-26 With careful nurturing
and "swaddling" of the Earth by a thick blanket of atmosphere, a world
ocean was formed.
Our Unique Ocean: an Example of Fine-Tuning
Since the early accretion-history of our neighboring planets Venus and
Mars should have been similar to the Earth's, we can infer from their present
lack of oceans that a set of fine-tuned conditions is necessary for water
to condense and remain as an ocean.
Venus, for instance, has about the same size and density as Earth and
was formed at a somewhat comparable distance from the Sun. As a result,
Venus is assumed to have formed from planetesimals containing H2O
in amounts similar to those that formed the Earth. In fact, the present
ratio of deuterium-to-hydrogen on Venus supports the idea that the planet
once had an initial mass of atmospheric water that was equal to the Earth's.27
Nevertheless, the early temperature conditions on Venus, a good deal warmer
than on Earth, were not conducive to condensing an ocean on its surface.28
Mars, on the other hand, has a landscape shaped by liquid water - even though the planet is 50% further from the Sun and has only a tenth of Earth's mass. However, the bulk of the water (except for ice at the poles and possibly some beneath its surface), is believed to have dissociated into the lighter molecules of hydrogen and oxygen which then escaped into space.29-30
To form and maintain an ocean, the Earth had just the right balance
of solar energy, internally derived heat, and heat created from the impact
and accretion process. The amount of water in the atmosphere was held at
just the right amount as God "weighed out the waters by measure" (Job 28:25).
The Earth both battled against and benefited from the erosive impacts of
large planetesimals, and as a result kept the necessary gravitational size
to retain enough water rather than losing it all to space. The magma "mantle"
layer and the atmosphere also worked in harmony to keep just the right
balance of water and other volatiles such as CO2. Even today,
processes within the mantle, chemical alteration of the oceanic crust beneath
the seas, and weathering of our continents have worked to maintain a life-sustaining
balance of water in the oceans and atmosphere.31-33
It has also been suggested that any water loss to space may have been made
up by continued input of water from meteoritic or comet material.34
Continents: The Earth Beneath Our Feet
Ultimately, the water of the ocean which was measured "in the palm of
His hand" (Isaiah 40:12) was used in the formation of the earth beneath
our feet. When the Earth had cooled and condensed an ocean of water, unstable
rock crusts were also formed atop the magma ocean, and these lay beneath
the sea. Subsequently, convection currents within the underlying mantle
moved portions of this crust (as plates) relative to one another, so that
new oceanic crust formed where plates were spreading apart, just as today.
As for the land we stand on - the continental crust - it formed by hydrous
processes within the magma at places where water-bearing oceanic crusts
sink into the magma or collide such that portions get carried down beneath
The resulting crust is unique among the known planets. It has a composition rich in SiO2, since H2O tends to make silica-rich magmas, in contrast with CO2 which makes silica-poor magmas (as we find on Mars).37 Since this silica-rich continental crust is less dense than the oceanic crust, it is lifted up and rises to the top. Just as commanded in Genesis, "let the dry land appear." In addition, the distribution of our continents suggests that following the formation of continental crust, God also "spread out the earth above the waters" (Psalms 136:6).
With all of this in mind, it should not escape our notice that - according to 2 Peter 3:5 and Psalm 24:2, respectively - "the earth was formed out of water and by water" and that "He has founded it upon the seas."
1. Stuart Ross Taylor, "Early Accretional History of
the Earth and the Moon-Forming Event," Lithos 30 (1993) pp. 207-221.
2. James Strong, "Hebrew and Aramaic Dictionary of the
Old Testament," in The New Strong's Exhaustive Concordance of the Bible,
(Nashville: Thomas Nelson, 1996), p. 135; see the word
3. H. B. Wiik, "The Chemical Composition of Some Stony
Meteorites," Geochemica et Cosmochimica 9 (1956), pp. 279-289.
4. Kazushige Tomeoka, "Phyllosilicate Veins in a CI
Meteorite: Evidence for Aqueous Alteration on the Parent Body," Nature
345 (1990), pp. 138-140.
5. D. S. Burnet et al, "A Test of the Smoothness
of the Elemental Abundances of Carbonaceous Chondrites," Geochim. cosmochim.
Acta 53 (1989), pp. 471-481.
6. E. M. Galimov, L. A. Bannikova, and V. L. Barsukov,
"The Material That Formed the Outer Shell of the Earth," Geochemistry
International 19-2 (1982), pp. 473-489.
7. E. M. Galimov, L. A. Bannikova, and V. L. Barsukov,
8. Marc Jovoy, "The Birth of the Earth's Atmosphere:
the Behaviour and Fate of Its Major Elements," Chemical Geology
147 (1998), pp. 11-25.
9. Constance M. Bertka and Yingwei Fei, "Implications
of Mars Pathfinder Data for the Accretion History of the Terrestrial Planets,"
281 (1998), pp. 1838-1840.
10. Kazushige Tomeoka, "Phyllosilicate Veins in a CI
Meteorite: Evidence for Aqueous Alteration on the Parent Body," Nature
345 (1990), pp. 138-140.
11. Magnus Endress, Ernst Zinner, and Adolf Bischoff,
"Early Aqueous Activity on Primitive Meteorite Parent Bodies," Nature
379 (1996), pp. 701-703.
12. Magnus Endress, Ernst Zinner, and Adolf Bischoff,
13. Kazushige Tomeoka, pp. 138-140.
14. J. R. Achworth and R. Hutchison, "Water in Non-Carbona-ceous
Stony Meteorites," Nature 256 (1975), p. 714.
15. Laura Garwin, "Comet Leaves a Trail in the Air,"Nature
392 (1998), pp. 754-755.
16. Manfred A. Lange, "Impact Vaporization of Water
in Hydrous Minerals," Eos 60 (1979), p. 308.
17. M. A. Lange and T. J. Ahrens, "The Evolution of
the Impact Generated Atmosphere," Icarus 51 (1982), pp. 96-120.
18. James A. Tyburczy, Benjamin Frisch, and Thomas
J. Ahrens, "Shock-Induced Volatile Loss from a Carbonaceous Chondrite:
Implications for Planetary Accretion," Earth and Planetary Science Letters
(1986), pp. 201-207.
19. James A. Tyburczy, Benjamin Frisch, and Thomas
J. Ahrens, pp. 201-207.
20. Yutaka Abe, "Physical State of the Very Early Earth,"
30 (1993), pp. 223-235.
21. Yutaka Abe and Takafumi Matsui, "The Formation
of an Impact-Generated H2O Atmosphere and Its Implications for
the Early Thermal History of the Earth," J. Geophys. Res. 90 (1985),
22. Yutaka Abe and Takafumi Matsui, "Early Evolution
of the Earth: Accretion, Atmosphere Formation, and Thermal History," J.
Geophys. Res. 91 (1986), pp. E291-E302.
23. Takafumi Matsui and Yutaka Abe, "Impact-Induced
Atmospheres and Oceans on Earth and Venus," Nature 322 (1986), pp.
24. Yutaka Abe and Takafumi Matsui, "Early Evolution
of the Earth: Accretion, Atmosphere Formation, and Thermal History," pp.
25. Yutaka Abe and Takafumi Matsui, "The Formation
of an Impact-Generated H2O Atmosphere and Its Implications for
the Early Thermal History of the Earth," pp. C545-C559.
26. Takafumi Matsui and Yutaka Abe, pp. 527-528.
27. T.M. Donahue, J. H. Hoffman, R. R. Hodges, Jr.,
and A. Watson, "Venus Was Wet; a Measurement of the Ratio of Deuterium
to Hydrogen," Science 216 (1982), pp. 630-633.
28. Takafumi Matsui and Yutaka Abe, pp. 527-528.
29. Vladimir A. Krasnopolsky, Michael J. Mumma, and
G. Randall Gladstone, "Detection of Atomic Deuterium in the Upper Atmosphere
of Mars," Science 280 (1998), pp. 1576-1580.
30. James Farquhar, Mark H. Thiemens, and Teresa Jackson,
"Amosphere-Surface Interactions on Mars: 17O Measurements of
Carbonate from ALH 84001," Science 280 (1998), pp. 1580-1582.
31. J. R. Lawrence and M. Taviani, "Extreme Hydrogen,
Oxygen and Carbon Isotope Anomalies in the Pore Waters and Carbonates of
the Sediments and Basalts from the Norwegian Sea: Methane and Hydrogen
from the Mantle?," Geochim. Cosmochim. Acta 52 (1988), pp. 2077-2083.
32. N. C. Flemming and D. G. Roberts, "Tectono-Eustatic
Changes in Sea Level and Seafloor Spreading," Nature 243 (1973),
33. Kiyoshi Kuramoto, "Accretion, Core Formation, H
and C Evolution of the Earth and Mars," Physics of the Earth and Planetary
Interiors 100 (1997), pp. 3-20.
34. Richard A. Kerr, "Spots Confirmed, Tiny Comets
Science 276 (1997), pp. 1333-1334.
35. Kiyoshi Kuramoto, pp. 5-6.
36. K. C. Condie, Plate Tectonics and Crustal Evolution,
Pergamon Press, 1989), pp 342-345.
37. Kiyoshi Kuramoto, p. 5.