Earth's Rotation

How Good Are Those Young-Earth Arguments?
A Close Look at Dr. Hovind's List of Young-Earth Arguments and Other Claims
by Dave E. Matson
Copyright © 1994-2002

Young-earth "proof" #20: The earth's rotation is slowing down, meaning that the earth can't be older than a few million years.

Presently, the earth's rotation is slowing down 0.005 seconds per year per year (Thwaites and Awbrey, 1982, p.19). At least Dr. Hovind doesn't use the horrendous rate of 1 second per year which Dr. Walter Brown employed as a result of a total misunderstanding of time keeping. I believe that Dr. Brown discarded that argument upon realizing his error, but don't expect it to disappear from the creationist literature. Only a towering optimist could expect that!

The actual rate of 0.005 seconds per year per year yields, if rolled back 4.6 billion years, a 14-hour day. The subject is a bit tricky the first time around, and I'm indebted to Thwaites and Awbrey (1982) whose fine article cleared away the cobwebs.

Let's do the calculation for 370 million years ago:

((0.005 sec/yr) x (370 million yr))/Year = (1,850,000 sec)/Year
= (21.4 days)/Year

Thus, at 370 million years ago, the earth had 21.4 extra days per year.

The total days then per year were: (365.25 + 21.4)days/Year = 386.65 days/Year.

(8766 hrs/Year)/(386.65 days/Year) = 22.7 hrs/day

If you do the same calculations for 4.6 billion years ago, you'll get the 14 hrs/day given by Drs. Thwaites and Awbrey. Thus, there is no problem here for mainstream science. Indeed, the present rate may be too high:

...the correct present rate of slowing of the earth's rotation is excessively high, because the present rate of spin is in a resonance mode with the back-and-forth

motion of the oceans' waters in the ocean basins. In past ages when the rotation rate was faster, the resonance was much less or nonexistent, resulting in a much more gradual slowing of the rotation rate. The most recent calculations indicate that the earth could be 4 to 5 billion years old and not have been spinning excessively fast or requiring the moon to be any closer to the earth than 225,000 kilometers (140,000 miles).

(Sonleitner, 1991)

A study of rugose corals from the Devonian (370 million years ago), initiated by John W. Wells of Cornell University in 1963, indicated that the year then had 400 days of about 22 hours each. For a discussion of coral clocks see Dott & Batten (1976, pp.248-249). Subsequent work with corals of Paleozoic, Mesozoic, and modern origin have produced highly revealing, if approximate, results.

Determinations of the same kind were made for algal deposits (stromatolites) of the Upper Cambrian (-510 m.y.) (Pannella et al., 1968). Plots of the collected data for the entire time span from Recent back through the Paleozoic Era showed a nonuniform increase in days per month going back in time, and from this it is inferred that tidal friction has not been uniform in that period.

(Strahler, 1987, p.147)

Studies of the chambered nautilus, for a time, was also proposed as a geologic clock by Kahn and Pompea. However, that effort ran into problems. Creationists still cite it in their efforts to discredit the coral clocks. Each case, of course, has to be judged on its own merits. The nautilus is not a coral, and the coral clocks are good enough to destroy the young-earth claims.

From the present slowing down of the earth's spin we get a day of 22.7 hours 370 million years ago; 370 million years ago is the approximate radiometric date of those rugose corals. And, a study of the rugose corals confirms that the day then was about 22 hours long. In this example we have a remarkable, if rough, agreement between two, diverse dating methods.

These facts spell "Old Earth."

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