On the accumulation of helium in geological time

摘要: In a former paper I gave an account of experiments on the presence helium in variety common minerals earth’s crust. The conclusion arrived at was that quantity is, general, determined by traces radio-active elements present. investigated were mostly palaeozoic age, and little attention paid to effect geological age content. If, however, accepted theory progressive accumulation change is correct, it evident must be all-important. present paper, subject considered from point view. There some difficulty finding suitable material for comparing content with their age. To make such comparison advantageously, necessary obtain very great range horizons, so oldest shall many times older than youngest. Thus becomes imperative get secondary tertiary strata. Most constituents these strata are unsuitable. For instance, derivative materials like clay sand rejected, because they have presumably been accumulating long before laid down stratigraphical position. chemical precipitates rocksalt gypsum free accurate measurements them difficult; while limestones are, lesser degree, open same objection.