Science in Christian Perspective
Meteoritic Influx and the Age of the Earth
From: JASA 28 (March 1976): 14-16.
The argument that the rate of meteoritic influx should give a young age for the earth is examined and shown to be fallacious. Recent measurements of influx show that no increase in nickel should result in ocean floor sediments. Lunar measurements of infall rates are consistent with the terrestrial value. Possible explanations which could be proposed by young earth creationists are shown to be inadequate.Introduction
Statement of the argument
A precise statement of the argument runs as follows: 1,2 In 1957 the Swedish geologist Pettersson3 estimated that the total influx of meteoritic dust upon the earth's surface was 14.3 x 106 tons/year (3.92 x 104 tons/day). His measurement was made by determining the amount of nickel in airborne dust which had been collected at 11,000 feet near the summit of Mauna Loa, Hawaii, and at 10,000 feet on Mt. Haleakala on the island of Maui.
The component of nickel averaged over all kinds of retrievable material is 2.5 per cent, whereas terrestrial material contains only 0.008 per cent nickel. Assuming that all of the nickel collected by Pettersson upon the mountain tops originated with extra-terrestrial matter, one need only multiply the measured quantity of nickel by 40 to obtain the total amount of dust from meteoritic sources. This comes to 14.3 x 106 tons/year. In five billion years, there would be a layer of dust 54 feet thick upon the surface of the earth if it were undisturbed. Clearly, this has not been the case. Hence, either a crustal mixing process has diluted this dust with enough terrestrial material to bring its concentration down to 0.008 per cent, or the added nickel has been swept into the oceans, thereby greatly increasing the amount of nickel in ocean floor sediments.
Whitcomb reject the crustal mixing hypothesis:
For example, - the average nickel content of meteorites is of the order of 2.5 percent, whereas nickel constitutes
only about 0.008 percent of the rocks of the earth's crust. Thus, about 312 times as much nickel per unit volume
occurs in meteorites as in the earth's crust. This means that the 54 ft. thickness of meteorite dust would have to
have been dispersed through a crustal thickness of at least 312 x 54 ft., or more than three miles, to yield the
present crustal nickel component percentage, even under the impossible assumption that there was no nickel in the
crust to begin with! Similar calculations could be made for cobalt and other important constituents of meteorites,
all testifying that there simply cannot have been meteoric dust falling on the earth at present rates throughout any
five billion years of geologic time!1 (p. 380)
Slusher dismisses the possibility that the extraterrestrial nickel could have been swept into the oceans:
the other hand, is acutally a rare element in terrestrial rocks and continental
sediments and is nearly nonexistent in ocean water and ocean sediments. This
seems to indicate a very short age for oceans. Taking the amount of nickel in
the ocean water and ocean sediments and using the rate at which nickel is being
added to the water from meteoritic material, the length of time of accumulation
turns out to be several thousand years rather than a few billion years.2
The above arguments hinge upon the correctness of Pettersson's value for the influx. Actually, many influx measurements have been made. Techniques vary from the use of high altitude rockets with collecting grids to deep-sea core samples. Accretion rates obtained by different methods vary from 102 to 109 tons/year. Results from identical methods also differ because of the
It is now up to young earth creationists to explain the accord between the accepted age of the earth and the rate of meteoritic infall.
sizes of the measured particles.4,5 One, therefore, looks for methods
which strive to measure all of the cosmic material regardless of size.
Terrestrial Influx Measurements
Non-selective terrestrial influx methods center around chemical analysis of various elements in ocean floor sediments. Core samples are taken from the ocean floor and the concentration of various elements is measured. Quantities which are in excess of terrestrial abundances are assumed to be extraterrestrial, Nickel, iridium and osmium have been used as indicators. These elements indicate infall rates from 8 x 104 (iridium) to 4 x 107 (nickel) tons/year. The 4 x 107 measurement, however, is suspect since it is not clear that the excess nickel was of cosmic origin.6 Excluding this value leaves a more realistic range for meteoritic infall rates, between 8 x 104 (iridium) tons/year to 3 x 106 (nickel) tons/year.
Even Pettersson feels that his measurement of 14.3 x 106 tons/year is high, and he prefers a figure of 5 x106 tons/Year.7 This seems to have been overlooked by Whitcomb, Morris and Slusher.
Nevertheless, the iridium and osmium measurements disagree with the nickel measurements for ocean floor sediments. The former indicate an influx of approximately 105 tons/year, or a factor of 30 lower than the nickel value. On the other band, the value from the iridium and osmium measurements are in agreement with determinations of the flux from nickel found in Antarctic ice where the probability of pollution by terrestrial nickel is much less than at other locations.8
Since iridium and osmium are ten-times less abundant in the earth's surface than nickel, they are more sensitive indicators of the influx of cosmic matter. It seems to indicate, therefore, that the mean accretion rate is about 101 tons/year.Lunar Influx Measurements
to terrestrial measurements, two lunar measurements have also been made of the
influx of cosmic matter.9,10 The concentrations of a number of trace
elements from core samples of the lunar surface reveal an excess of rare-earth
elements when compared to their value in lunar rocks. The enrichment of these
trace elements on the lunar surface can be accounted for by a 1.5 to 1.9 per
cent addition of carbonaceous chondrite-like material. The total addition of
this matter corresponds to an influx rate of 2.9 x 10-9 gram per square
centimeter per year (grm/cm2yr) to 3.8 x 10-9 gm/cm2
yr. These values compare favorably with the analogous estimate for the earth.
(105 tons/year corresponds to 1.2 x 10-8 gm/cm2yr).
The value for the meteoritic infall rate used by Whitcomb, Morris and Slusher is too large by a factor of 140. The lunar results of Keays et al and Ganapatby et al indicate that carbonaceous chrondrite-like material is the major contributor to the accreted matter. The nickel content of carbonaceous chrondrites is 1.03 per cent, or a factor of 2.5 less than the figure computed from retrievable meteorites." Since the total cosmic infall is 140 times less than Pettersson's value, the depth of crustal mixing required to disperse the excess nickel is 2.5 x 140=350 times less than the value given by Whitcomb and Morris, or 48 feet! Driving down a highway that has been cut through a small hill will reveal more crustal mixing than this!
The increase of nickel in ocean floor sediments also presents no problem. The total amount of weathered material carried into the oceans by the major rivers of the world has been estimated as 30 x 1015 grams/year, or 3.26 x 1010 tons/year.12 Since the nickel content of crustal material is 0.008 per cent, 2.6 x 106 tons of terrestrial nickel is carried into the oceans each year. The total amount of extraterrestrial nickel is 103 tons/year, which is insignificant when compared to the terrestrial value. Contrary to Slusher's claim, no appreciable increase in the nickel content of the oceans is expected from cosmic matter.
The rate of infall was determined by assuming a 4.5 x 109 year age for the earth, which is rejected by young earth creationists. They may accept the above value for the total influx of cosmic material, but they may argue that it has been falling at a constant rate for only the past 10,000 years. Such an assumption necessitates an increase in the infall rate by a factor of 4.5 x 103, or 4.5 x 1010 tons/year (1.2 x 108 tons/day).
Direct measurement of airborne particles and lunar micrometeoroid flux, however, give influx values which are five orders of magnitude below this figure.13,14 Hence, the assumption of a constant influx over such a short period of time must be rejected.
Another possible explanation would be that the entire amount of material was dumped upon the earth and the moon at one time either before or during the Flood. The Flood could then have distributed the cosmic matter throughout the earth's crust and ocean floor sediments.
But this is nothing more than ad hoc speculation. If the Flood distributed the iridium and the osmium uniformly throughout the ocean floor sediments, then it should have similarly distributed other elements as well. But this is not the case.
For example, thorium-230 and proactinium-231 are two radioactive elements with similar chemical properties. Thorium-230 has a half-life of 75,000 years and proactinium-231 has a half-life of 34,300 years. Both elements form insoluble phosphates which precipitate in the oceans. Hence, both thorium-230 and proactinium-231 are removed from ocean water ani deposited upon the ocean floor.
Now, suppose all of the thorium-230 and the proactinium-231 found in ocean floor sediments had been deposited over the course of one year by the Flood. One should expect either the same concentration of tborium230 and proactinium-231 throughout all the sedimentary layers; or, one would expect that the insoluble tborium230 and proactinium-231 phosphates remained suspended in the turbulent Flood waters and were then deposited upon the surface of the ocean floor as the turbulence subsided. In the latter case, one would expect a heavy concentration of thorium-230 and proactinium-231 near the top of the ocean floor covered by a few centimeters of sediment corresponding to the decomposition of material since the Flood.
On the other hand, if the thorium-230 and the roactinium-231 have been deposited at a constant rate or a time which is long compared to their half-lives, then one would expect a logarithmic decrease in the concentration of these elements with increasing sedimentary depth. This is characteristic of radioactive decay, And this is exactly what is found to a depth of ten meters in a Caribbean core! 15 A similar analysis for sedimentary depths up to 140 meters using potassium/argon decay also gives the characteristic logarithmic decrease.
Notice that I have not relied upon radioactive techniques for the purpose of establishing the absolute ages of ocean floor sediments, I have shown only that the logarithmic decrease in the concentration of radioactive elements as a function of increasing sedimentary depth argues strongly against rapid deposition of these sediments. Hence, one should reject any attempt to explain either the accumulation of ocean floor sediments or of meteoric material during the time of the Flood.
One concludes that the meteoritic influx argument of Whitcomb, Morris and Slusher is invalid. In fact, it is now up to young earth creationists to explain the accord between the accepted age of the earth and the rate of meteoritic infall.Acknowledgements
1John C. Whitcomb, Jr. and Henry M. Morris, The Genesis Flood (Philadelphia: Presbyterian and Reformed, 11996611Baker, 1969), pp. 378-380.
2Harold S. Slusher, "Some Astronomical Evidences for a Youthful Solar System," Creation Research Society Quarterly (June 1971): 55-57.
3H. -Pettersson, "Cosmic Spherules and Meteoritic Dust," Scientific American 202 (February 1960): 132.4D. W. Parkin and D. Tilles, "Influx measurements of Extraterrestial Material," Science 159 (March 1968): 936-946.
and Anders, Geochim et Cosmochim. Acta, pp. 642-643.
7Pettersson, Sci. Am., p. 132.
9Reid R. Keays, et al. "Trace Elements and Radioactivity in Lunar Rocks: Implications for Meteorite Infall, Solar-Wind Flux and Formation Conditions of Moon," Science 167 (January 1970): 490-493.
10R. Ganapathy, Reid R. Keays and Edward Anders, "Apollo 12 Lunar Samples: Trace Element Analysis of a Core and the Uniformity of the Regolith," Science 170 (October 1970): 533-535.11Barker and Anders, Geochim et Cosmochim. Acta, p. 642.
12Karl K. Turekian, Oceans. Foundations of Earth Science Series, ed. A. Lee McAlester (Englewood Cliffs: PrenticeHall, 1968), p. 27.13Parkin and Tilles, Science, p. 944.
14Leonard D. Jaffe, "Lunar Surface: Changes in 31 Months and Micrometeroid Flux," Science 170 (December 1970), 1092-1094.15Turekian, Oceans, pp. 61-72.