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Really Out of Date!
Ken Glasziou
More than twenty five years ago, when reading The Urantia Book account of the early geological history of our planet, I noticed some statements about the growth of the planet and its moon, and also ocean formation, that struck me as being rather odd. However this material was followed by the book's account of continental breakup and the subsequent continental drift. I found this exciting--and that caused me to overlook the "odd" material until quite recently.
The book's account of continental drift was exceedingly prophetic if made in 1934 or even up to the time of first publication in 1955. I had once done a three semester undergraduate course in geology and distinctly remembered how the lecturer had quickly dismissed the continental drift theory of Alfred Wegener with the brief comment that there were no known physical forces that could possibly account for the splitting apart of whole continents.
A quick check on the history of the continental drift theory revealed the enormous opposition it received from leading geologists in the USA and Britain, among them Rollin Chamberlin and Sir Harold Geoffreys.
This opposition remained until around 1960 when geophysical surveys of the mid-ocean Atlantic ridge revealed that, as the Earth's mantle melted, the molten rock was forced upwards thus causing the sea floor spreading that could account for continental drift.
Further clinching the prophetic nature of the Urantia Book account, later geophysical work revealed that the initial breakup of a supercontinent, as proposed by Wegener, actually occurred much earlier than the 200 to 250 million years he allowed. Gradually this date was pushed back to about 500 to 600 million years to finally coincide with the Urantia Book's 750 million years BCE.
My memory of the book's "odd" account for the early formation of our planet-moon system was stimulated by a recent TV documentary on the Apollo missions to the moon starting back in the 1970's, and the contemporaneous Russian missions that also contributed a tremendous amount of valuable new scientific knowledge.
Particularly the Americans, but also the Russians, had done remarkable things that now allow us to get a much better picture of how our Earth-Moon system developed and grew. Much of this was brought about because of the extensive sampling of geological materials from many sites on both sides of the Moon, including the highest mountains, the larva plains known as mares, and many of the impact craters formed by meteors.
It was also fortunate that much of the analytical work did not take place prior to the new and quite remarkable techniques and new technology (including zircons and ion probes) for dating of rock samples becoming well understood.
Very briefly stated, results, such as their identical ratio of oxygen isotopes (which is different from meteoric material), showed that although the basic materials from which the Earth and its satellite Moon developed are entirely similar, nevertheless there are important differences that must be explained.
Three of these differences are the complete lack of water associated with minerals and rocks from the Moon, the iron content at 30% for the Earth and 2% for the Moon, and the average density at 5.5 g/cc for the Earth and 3.3 for the Moon--the latter being about the same as the density of the Earth's crust. Heavily crystalline Moon rock samples that are more than 4 billion years of age also showed this material was once molten.
Radiometric dating showed that Moon samples from the mountain regions go back beyond four billion years from the present while the basaltic rocks from the mares formed between 3.9 and 3.1 billion years ago.
Prior to the data from these Moon missions becoming available there were three main theories for formation of our Earth-Moon system--co-accretion, fission, and capture.
The co-accretion hypothesis suggests that the moon and the Earth were formed together from a primordial cloud of gas and dust.
In the fission scenario, a fluid proto-Earth spun so rapidly that it ejected a mass of material that became the Moon.
The capture hypothesis has it that the Moon formed elsewhere to be later captured in the strong gravitational field of the Earth.
Co-accretion is the means by which The Urantia Book says our Earth-Moon system formed together. There are problems. The hypothesis cannot account for the observed angular momentum of the system, nor the absence of bound water in Moon rocks, the depletion of iron, the density differences, nor the radiometric data.
The fission scenario has been extensively modeled but no one has been able to produce a computer model that will fit the known data.
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