Word: field
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Dates: during 1940-1949
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Cadets spend time learning to play trombones, trumpets, accordions, euphoniums, graduate with the rank of probationary lieutenant. After a year of correspondence study and strict probation, they are commissioned as second lieutenants with the legal standing of ordained ministers. From there they advance through the field ranks: first lieutenant, captain, major; through the staff ranks: brigadier, lieutenant-colonel, colonel, lieutenant-commissioner, commissioner...
Fossil Magnetism. The earth has a powerful magnetic field, but no one knows what creates it. In hope of finding out, the Carnegie scientists studied the magnetism in ancient sedimentary rocks...
When silt sinks slowly to the bottom of an ocean or lake, the magnetic particles in it line up with the earth's magnetic field like tiny compass needles. When the silt hardens into rock, the magnetic particles are "frozen" so that they cannot move. The Carnegie scientists found that even when the rock layer is folded by geological forces, the magnetic particles keep their alignment, pointing accurately around the curves of the folds. Even in layers known to be 200 million years old, the rock keeps its magnetism...
...million years old which they took from flat-lying strata in the western U.S. proved to have a magnetism pointing in about the same direction as present-day compass needles. The conclusion was that when the rocks were laid down as silt, the earth's magnetic field was about as it is today...
...Carnegie scientists were cautious about jumping to conclusions. But at least two conclusions are possible: 1) that the earth's magnetic field has shifted radically since 200 million years ago, or 2) that the North American continent, including Maryland, was once near the south pole and has since drifted slowly to its present position...