Hydrogen isotope biogeochemistry reactors in 1988, but nuclear weapons testing in the 1950s added large spikes of radioactive elements to the atmosphere, especially radiocarbon and tritium. This complicated measurements for geologists using radiometric dating of carbon. However, some oceanographers benefited from the tritium increase, utilizing the signal in the water to trace physical mixing of water masses. In biogeochemistry, scientists focused primarily on the stable isotope of deuterium as a tracer for environmental processes, especially the water cycle. The American geochemist Harmon Craig, once a graduate student of Urey's, discovered the relationship between rainwater's hydrogen and oxygen isotope ratios. The linear correlation between
Archaeological science archaeological strata and artifacts. Some of the most important dating techniques include: Another important subdiscipline of archaeometry is the study of artifacts. Archaeometrists have used a variety of methods to analyze artifacts, either to determine more about their composition, or to determine their provenance. These techniques include: Lead, strontium and oxygen isotope analysis can also test human remains to estimate the diets and even the birthplaces of a study's subjects. Provenance analysis has the potential to determine the original source of the materials used, for example, to make a particular artifact. This can show how far the artifact has traveled