Biographical Memoirs Volume 66 (1995) / Chapter Skim
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Charles Snowden Piggot
Charles Snowden Piggot
Pages 246-265
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From page 247... ...
It is these past events that reveal valuable information about geologic processes at work on land as well as in the ocean basins. His investigations finally produced reliable dates on se~liments and sedimentation rates from the North AtIan tic Ocean and the Caribbean Basin over a time span of some 300,000 years.
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From page 248... ...
He provided the lead samples that Aston used to produce the first isotopic composition data for "common" lead and radiogenic lead from uranium decay. He received the Orcier of the British Empire for work on mine disposal in World War IT and the Bronze Star from the U.S.
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From page 249... ...
He also taught chemistry in the School of Dentistry, which later merged with the Maryland Medical School. Finding no suitable text book he wrote Piggot's Dental Chemistry, a standard text book for many years.
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From page 250... ...
"We worked for over a year without a single positive or encouraging result. While working on a form of very finely divided manganese dioxide ~ had the luck to add a small amount of silver oxide and had the good fortune to obtain a catalyst which completely oxidized carbon monoxide to carbon dioxide whenever the incoming air mixture was thoroughly dry and there was sufficient oxygen to link up with the carbon monoxide," said Piggot in an
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From page 251... ...
industrial Chemical Company in a research laboratory devoted to preparing chemical products from ethyl alcohol and acetic acid as the principal starting substances. They developed processes for production of absolute alcohol in tank car lots; also anhydrous ethyl acetate, absolute ethyl ether, and ethylene gas.
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From page 252... ...
In 1925 he joined the staff of the Geophysical Laboratory of the Carnegie Institution of Washington to conduct research into the significance of radioactivity in geophysical phenomena. This work involved studies of the radium content of the various layers of the earth's crust with resultant heat production and efforts to improve the determination of geologic time by comparing the amounts of lead associated with its radioactive parent, uranium.
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From page 253... ...
Upon arrival at the Geophysical Laboratory Piggot constructed an apparatus for determination of the radium content of igneous rocks by measurement of the activity of radon gas that was released by fusion of samples in carbonate fluxes. The resulting publications on the radium content of granites and their constituent minerals en c!
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From page 254... ...
In addition, colleagues at the Department of Terrestrial Magnetism used the cores to measure changes in orientation of the earth's magnetic field over the past several hundred thousand years. Piggot realizer} that the sediment layers in the ocean bottom would reveal a valuable historical record of the ocean basins, which should provide useful information about processes that have occurred on land.
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From page 255... ...
The rocks and pebbles and sand brought by ice, the clay and mud brought by rivers and ocean currents, the skeletons of marine organisms which lived and died and evolved into various forms throughout the ages constitute this record.... In addition to these records of life and its many changes there exists a chemical and a physical record.
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From page 256... ...
The results of the papers Piggot and Urry published between 1939 and 1941 were summarized and evaluated in 1942 in a landmark paper in Bulletin of the Geological Society of America, which reported radium results on cores from the North Atlantic Ocean, the Caribbean Basin, anct Pacific Ocean reck clay. Depending upon core length and sedimentation rates the cores spanned periods of time reaching back 10,000 to 300,000 years.
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From page 257... ...
, fulfilling the expectations Piggot had expressed when he first started work on ocean sediments. They further showed that clates from a core in the Cayman Trough of the Caribbean Sea yielded results in close agreement with the North AtIan tic data.
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From page 258... ...
They also found that the surficial clay core surface contained 226Ra in excess of the amount required for secular equilibrium with the 230Th parent, whereas calcareous sediments and oozes from the Atian tic Ocean normally contained less 226Ra than required for secular equilibrium. According to their data sedimentation rates in the Caribbean Basin increased starting 7,000 years ago compared to rates during the Wisconsin glacial epoch.
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From page 259... ...
the questions Piggot had asked at the start of the experiments showing that the high concentrations of Ra in ocean sediments were a surface effect and that 230Th abundances in marine sediments were higher than those required for secular equilibrium with 238U. With the aid of the coring device it was possible to use that relationship to clate sediment horizons and thereby ascertain sedimentation rates.
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From page 260... ...
His assignment was to devise means for evaluating damage to ordnance equipment and to provide underwater photography using men en cl equipment from his mine disposal experience. He received a Bronze Star for that service.
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From page 261... ...
Records from the Geophysical Laboratory and an obituary in The Washington Post, dated July 9, 1973, yielded additional information covering some of his professional activities, publications, and awards. I am indebted to Gordon L
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From page 262... ...
IV. Location and association of radium in igneous rocks.
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From page 263... ...
Geological Survey Professional paper 159-A. Geology and biology of North Atlantic deep-sea cores between Newfoundland and Ireland.
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From page 264... ...
Urry. Time relations in ocean sediments.
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