Hans E. Suess

On the Relationship Between Radiocarbon Dates and True Sample Ages

A summary is given of current knowledge pertaining to differences between radiocarbon ages and true ages and of the status of empirical calibration of the radiocarbon time scale. Recent measurements have shown that a more complicated relation exists between radiocarbon age and exact calendar age of samples than was assumed by Libby; the relation can be derived empirically by determination of radiocarbon contents of samples of known age. Causes for fluctuations of the C-14 activity of atmospheric CO (sub 2) are reviewed briefly. Work of tree-ring laboratories shoould make available precisely dated samples many thousand years old for use as an empirical correction table relating radiocarbon ages to true ages of the sample; radiocarbon and 0true ages for the last 2,000 years are tabulated. Only one C-14 age exwxists for each calendar year but a radiocarbon age may correspond to more than one true age.

On the origin of gas-rich meteorites

Meteorites that contain large amounts of primordial rare gases, i.e. the so-called gas-rich meteorites, always show a light-dark structure. They consist of light parts imbedded in a matrix of much darker material. Only the dark material contains the rare gases. Mineralogical and chemical evidence shows that gas content and light-dark structure of this class of meteorites cannot have originated simultaneously with the formation of sulfides, nor can it have been produced by violent shocks. Although the chemical composition of the minerals in the light and in the dark parts is practically identical, the structure of these meteorites is not that of a pseudobreccia produced in situ, but that of a true polymict breccia formed by agglomeration of various types of fragments. Content and distribution of primordial rare gases and their isotopes in these meteorites, in particular according to the results obtained at Mainz, can best be explained by assuming incorporation of the gases by particle radiation such as solar wind. A possible relationship to comets is mentioned.

Can enstatite meteorites form from a nebula of solar composition

Abstract Doubts have been expressed as to whether solar matter is sufficiently reducing to explain the minerals occurring in the enstatite chondrites and in the enstatite achondrites. Thermodynamic calculations on the stabilities of TiN, Si2N2O, CaS and silicon-bearing iron metal show that these substances can form under equilibrium conditions from a nebula of solar composition provided that the total pressure exceeds ~ 1 atm and that thermodynamic equilibria are frozen in at near-formation temperatures.

Secular non-random variations of cosmogenic carbon-14 in the terrestrial atmosphere

Abstract The time dependence of the14C content of bristlecone pine wood samples dated by their tree rings and grown during the last 8000 years was examined. The14C values as measured by the La Jolla Radiocarbon Laboratory were used for the investigation. Two different smoothing techniques were used for constructing values for equal time intervals. In this manner the introduction of regularities, that could have resulted from applied mathematical techniques, could be excluded. There is good evidence for non-random features in the power spectrum, in particular for a 200-year periodicity. The regularities in the power spectrum are further indications supporting the assumption that the14C variations reflect a property of the sun.

RADIOCARBON CONTENT AND TERRESTRIAL AGE OF TWELVE STONY METEORITES AND ONE IRON METEORITE

Abstract The radiocarbon content of twelve stony meteorites, six with observed time-of-fall and the others finds, and that of an iron, (Aroos), has been determined in the La Jolla Radio-carbon Laboratory. The average contemporaneous radiocarbon content of the falls was found to correspond to 48.2 disintegrations/min. A much lower value of 5.4 disintegrations/min was found for the iron. Of the six finds, two were found to be Pleistocene. The average C14 content of the finds investigated indicates that terrestrial ages of the order of a thousand years are quite common.

La Jolla natural radiocarbon measurements, [Part] 1.

The recently established low-level radiation laboratory of Scripps Institution of Oceanography has been measuring radiocarbon since Aug. 1957. Through 1959 about 160 samples have been measured. In the radiocarbon tests, the La Jolla laboratory staff utilizes the technique, with acetylene as the counting gas, that was developed at the U.S. Geological Survey. Until March 1959 only one set of equipment was in service, with a counter somewhat smaller than either of the 2 used in Washington, having a sensitive volume of approximately 0.6 liter. In March 1959 an Oeschger-Houtermans counter, manufactured at the Physical Institute of the University of Bern, Switzerland, was installed. It operates with a background of less than 2.0 counts/min., decreasing with filling pressure, and a sensitive volume of 1.3 liters. This counter proved to be more stable than the ordinary counters, and it can be operated at pressures as low as 440 mm., at which a background as low as 1.2 counts/min. can be attained. Therefore, this counter proves to be superior also in the measurement of relatively small samples. The installation of one or more additional counters is being considered, with the aim of increasing the annual output of tests. Shell dates reported in this paper are calculated (as in U.S.G.S. I) from 19th century wood as a reference standard, without correction for any supposed fractionation of isotopes. This procedure has been adopted because in general, within the errors of measurement, the activity of 19th century wood corresponds to that of modern shell, despite the differences in the equilibrium distribution of the isotopes as shown by C (super 13) analyses.

La Jolla natural radiocarbon measurements IV.

Carbon-14 dates are reported for both geologic and archeologic samples from Alaska, California, Colorado, Hawaii, Oregon, Mexico, Brazil, Northern Ireland, Africa, Australia, and Indonesia. Results, grouped geographically, show sea-level changes and shore processes in Alaska, California, Hawaii, Mexico, Brazil, Northern Ireland, Australia, and Indonesia; deep-sea sediments in Gulf of Alaska and Golfo de California; old and modern lake sediments in Africa, California, and Mexico; pedogenesis and alluviation in California and Mexico; geochemical processes in carbonates from California, Colorado, and Mexico; paleozoography in Northern Ireland; and archeology in Oregon, California, and Mexico.

Can the ordinary chondrites have condensed from a gas phase

The conditions under which ordinary chondrites containing iron in three different chemical states can form in thermodynamic equilibrium with a gas phase are calculated. Hydrogen depletion factors of 102–103 are obtained and the formation of liquid condensates from residual gases occurs at pressures (prior to hydrogen depletion) of ⪸1 atm.

Climatic changes and the atmospheric radiocarbon level

Abstract Fluctuations in the atmospheric radiocarbon level observed by measurements of the radiocarbon content of tree-ring-dated-wood are caused by changes in the geomagnetic field and in the activity of the sun. There are also indications for correlations of these carbon-14 fluctuations with climatic changes. If one assumes that the observed correlations are significant, then one might suspect that major climatic changes have occurred during the eighth century B.C. and the thirty-third century B.C.

Natural Tritium Measurements by Ethane Counting

A method is described for the synthesis of ethane from hydrogen that is at present used for the counting of low-level tritium activity at the La Jolla tritium laboratory. The reaction procedure is simple and involves the mixing of the hydrogen with acetylene over a colloidal palladium catalyst. Counting characteristics of ethane are found to be ideal. With a 1-liter counter filled to three atmospheres of ethane, only a tenfold tritium enrichment is necessary in order to obtain a sensitivity of 0.32 counts per minute per tritium unit.