Earth Science Problems Research Articles

Review Lecture: Experiment and the crust of the Earth

In this review I should like to consider our progress in unravelling some problems in Earth science, particularly problems where experiment has led to a much deeper understanding of observations concerning the formation of rocks now found at the surface of the Earth. While geophysical probes into the Earth’s interior become increasingly sophisticated, I think it is still true that most of our models of Earth properties and materials at depth, are based on observations and experiments on materials seen at the surface if we include meteorites in the sample. It is also true that crustal phenomena provide most of the evidence concerning the dynamics and evolution of the entire Earth.

The Analysis of Aggregates of Orientation Data in the Earth Sciences

Investigations involving orientations permeate virtually all branches of the earth sciences. Statistical methodology depends upon the requirements of the subject matter and the availability of suitable methods. Some developments in other sciences apply to earth-science problems. In all orientation studies in which the spread of data occupies an appreciable part of the period, periodicity presents special problems. We require clarification of statements of precision of measurement; the order of measuring error may not be constant for all observations of one type. Most angle-sampling problems are believed to be similar to those of non-periodic variables. Application of variance analysis to the design of many investigations must await determination of variance properties which are as yet unknown. Sample-size criteria are now best derived by sequential sampling. Statistical models and measures of departure from the models must be carefully defined. Operational definitions provide considerable insight into the...

Symposium on the measurement of geologic time

The last time that a symposium on the topic of the measurement of geologic time took place was at the 1933 Meeting of the American Association for the Advancement of Science in Chicago. Those who may be interested in the progress made in this field may care to compare the topics covered by the papers on these two occasions. In 1933 there were no talks dealing with the age of the Earth's crust, with the measurement of lead isotope ratios, with “carbon‐14,” or with the rubidium‐strontium ratio method, for the simple reason that these techniques had not then been thought of, much less developed. We feel that the present general audience of active workers in all fields of geophysics and geochemistry will be interested to hear from the experts of these new developments in the application of physical and chemical techniques to a very fundamental series of problems in Earth science, and also to learn of recent progress in fields that may now be termed “classical.”