Earth's Core & Crust

Harvard, having assembled funds for a five-year survey of Earth's construction, conducted a wordy colloquium on the subject in Cambridge last week. Assembled were members of the Geological Society, the Paleontological Society and the Mineralogical Society (all "of America") who recounted terrestrial fact and surmise. Some complementary information proceeded from the A. A. A. S. meeting (see above). Items:

P: Of Earth's volume, 99.9% "must forever remain invisible and untouchable." Yet from the indirect evidence of earthquakes, volcanoes, mines, oil wells, igneous rocks on the weathered surface it was possible for Professor Reginald Aid-worth Daly (Harvard) to estimate the Earth's outer crust as 40 mi. thick in continental areas (thicker under seas); the next shell 1,800 mi. thick, composed of glassy rock more rigid than steel; the core a ball of molten iron 7,000 mi. in diameter, under 15 to 50 million pounds pressure per square inch.

P: The thin crust is elastic, yields to strains and stresses. Places in Massachusetts, New Hampshire and Maine are 800 ft. higher than they were 30,000 years ago when the Wisconsin Glacier pressed down upon New England. When the glacier melted the land sprang back to normal elevation. Another 100,000 years must pass before a similar glacier could descend upon & depress the region--Irving Bollard Crosby (Boston), Richard J. Lougee (Columbia).

P: The ends of the U. S. Atlantic seaboard are rising, while the middle falls. Portland, Me. and Charleston. S. C. gain 7 to 15 in. elevation in a century. Boston. New York, Atlantic City, Philadelphia and Baltimore subside 3.5 to 11.5 in. a century. Key West seems stationary. The rises & falls seem to be rhythmic. Boston, now sinking, was on the up between 1847 and 1876, with most of the elevation gained between 1857 & 1858. The sudden gain, surmises Dr. William Fitch Cheney Jr. (Connecticut Agricultural College), was related to the Naples earthquake of 1857. Charleston had an earthquake in 1886 which may account for the movements at Charleston and Baltimore.

P: As the Moon passes over the Atlantic the distance between London and Manhattan stretches by 63 ft., possibly the result of tidal pull.--Alfred Lee Loomis (Manhattan), Professor Harlan True Stetson (Ohio Wesleyan).

P: Oklahoma's Professor Frank Armon Melton noted in an airplane mosaic map of Horry County, S. C. some strangely regular furrows in the terrain. Later with Professor William Schriever (University of Oklahoma) he examined the ground directly, learned that the people of the neighborhood called the vast grooves "bays." The two scholars found more than 1,500 large "bays" (some 2 mi. long) between Norfolk, Va. and the Savannah River, decided that 100,000 to 1,000,000 years ago a comet must have grazed the earth. The comet head composed of hundreds of separate meteors, must have been 400 mi. in diameter. It nicked the Earth from northwest to southeast, scoured 40,000 sq. mi. of the Piedmont, ripped over 150,000 sq. mi. of ocean.

P: "If you have a popcorn machine, you know how fast the machine converts popcorn to fluffy balls. If you measure the pile of popped corn, you know how long the machine has been working, if it has been operated at a constant rate of production."--Tufts' Alfred Church Lane. With many such "ifs" Professor Lane estimates the present age of uraninite as 1,070,000,000 years, of pitchblende as 1,300,000,000 years.* From those two estimates he sets the age of the Earth at between two and three billion years.

*Canada's pitchblende deposits at Great Bear Lake are about ready to produce 1 gm. of radium for 10 tons of ore in six weeks and a score of refining steps (against the Belgian Congo method of 3 mo. and 40 steps). Some 4,000 gm. of radium concentrates are ready for the refinery at Port Hope, Ontario. The Canadian process promises much cheap radium for the world, new wealth for Canada.

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