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Lunar Rocks and Velikovsky's Claims
An associate professor of physics in the geophysics division, University of Toronto, Dr. Derek York is analyzing lunar samples as a Foreign Principal Investigator, Apollo Project.
In 1896, a 44-year old French professor, Henri Becquerel discovered that uranium compounds emitted rays which penetrated glass and paper and blackened photographic plates. Becquerel had discovered what we call radioactivity. Uranium atoms are unstable and a group of them will very slowly (that is over hundreds of millions of years) spontaneously change into the stable element lead. This transformation is accompanied by the emission of the rays which Becquerel detected. The important thing about uranium radioactivity from our point of view is that it goes on at a rate characteristic of uranium and this rate can not be altered by heating the uranium, hitting it with a hammer or exposing it to a vacuum. Radioactivity, ticking steadily away, therefore provides us with a natural clock.
All rocks contain at least traces of uranium and can therefore be dated using the uranium clock. Suppose we had a piece of terrestrial rock whose age we wished to calculate. We would firstly measure the number of uranium and lead atoms it now contains. Imagine that we found in this rock seven million atoms of uranium and three million atoms of lead. Then we would argue that all these three million lead atoms were originally uranium atoms and that when this rock originally solidified (say from molten lava) it contained ten million uranium atoms and no lead. By the time we reach the present, three million (that is 30 per cent) of the uranium atoms have changed into three million lead atoms. We would, therefore, conclude that since this rock is old enough for 30 percent of its original uranium content to have decayed to lead, it must be about two billion years old. This is because we know from the results of nuclear physics that it always takes about two billion years for 30 per cent of a set of uranium (U-238) atoms to decay into lead. Thus in general by measuring what fraction of the uranium originally trapped in a rock at solidification has changed to lead, we can say how long ago that rock did in fact solidify.
Apart from the uranium-lead clock, we can also use the potassium-argon and rubidium-strontium clocks. For potassium slowly changes radioactively into argon as does rubidium into strontium. So by measuring what fraction of the original potassium in a rock has changed into argon (or what fraction of the original rubidium has decayed to strontium) we can again calculate its age. In the past twenty years, these three radioactive clocks have been studied intensively for terrestrial rocks and meteorites in laboratories in many countries. These studies have revealed that the oldest rocks formed on the earth are about four billion years old and are found in Southwest Greenland. The oldest rocks so far analyzed in North America are in Minnesota and were formed about three and a half billion years ago. Most terrestrial rocks, however, are younger than this. The Columbia River volcanics in Oregon, for example, were mainly erupted a mere fifteen million years ago. The meteorites, in contrast, almost all date at about 4.5 billion years. These are chunks of rock and iron-nickel alloy which bombard the earth-moon system.
The general conclusion from these thousands of age analyses is that the meteorites formed somewhere in the solar system about 4.5 billion years ago and that the earth formed essentially at the same time.
When the Apollo XI astronauts returned to earth in 1969, the lunar samples were immediately examined for the readings on their uranium-lead, potassium-argon and rubidium-strontium clocks. The potassium-argon and rubidium-strontium results were in essential agreement that the rocks analyzed were last molten on the moon approximately 3.6 billion years ago. Because of the low concentrations of uranium and lead found, the uranium-lead technique was less definitive, but it also agreed that the rocks were formed somewhere between three billion and five billion years ago.
Succeeding missions have yielded fairly similar results. The Apollo XII rocks were last molten about 3.3 billion years ago; the Apollo XIV rocks formed about 3.9 billion years ago; most of the Apollo XV rocks crystallized at about the same time as the Apollo XII samples, about 3.3 billion years ago.
Obviously, the four lunar sites so far visited on Apollo missions are all characterized by very old rocks, that is rocks which evidently last solidified from a fluid state ever three billion years ago. If these sites are not atypical, we may therefore conclude that the moon was a very active place geologically between three billion and four billion years ago, undergoing severe meteoritic bombardment and internally generated volcanic activity. Since then it has been a remarkably quiet body suffering only the occasional large meteorite impact. Subsequent modification of the surface features has been mainly erosion due to the impact of small meteorites, cosmic rays and particles from the sun. This is in great contrast with the earth's history which has been one of continued volcanic and mountain-building activity up to the present day.
The fine-grained soils (as distinct from the rocks) returned from the moon are probably the nearest we will come to having an average moon sample. These date by the rubidium-strontium and uranium-lead techniques at 4.4 to 4.6 billion years old and probably indicate that the moon as a whole formed at about the same time as the earth and the meteorites. Potassium-argon dating of the soils is complicated by the presence in the soils of large volumes of all the rare gases (helium, neon, argon, krypton and xenon) whose presence remains to be finally explained.
In his book Worlds in Collision Dr. I. Velikovsky suggested that significant areas of the moon's surface were melted during close approaches by Mars within the past few thousand years. As may be seen from this article, no evidence of this has been found in studies of the uranium-lead, potassium-argon and rubidium-strontium clocks. We, therefore, appear to be faced with the following possibilities: (a) this part of Velikovsky's thesis is wrong; (b) Velikovsky is right but the four Apollo landings and the Soviet Luna 16 landing were in areas which escaped the "catastrophes" referred to by Velikovsky; (c) there is something seriously wrong with the radioactive clocks or our readings of them. There seems to be no good reason for choosing possibility (c) and the evidence favours (a) over (b).
PENSÉE Journal I