Kelvin's estimate of about $10^{8}$ years for the age of the earth, based on the time required for an initially uniform and hot thermal structure to decay to the presently observed surface temperature gradient, is briefly reviewed. The later realization that the earth was at least several billion years old ($4.5 \times 10^{9} years$) posed a dilemma: How to reconcile thermal evolution with this great age? Radiogenic heat production alone is demonstrably insufficient to effect the reconciliation and, in the end, it is mantle convection, with its ability to exploit the entire internal heat of the earth, that provides the way out. The present usefulness of thermal structure as a measure of age (age now taken to mean local as opposed to global age) is reviewed for oceanic and continental regions. As for Kelvin, he was quite right in arguing that the earth's age was not only finite but measurable, measurable however by methods he did not anticipate.
Current issues are now on the Chicago Journals website. Read the latest issue.One of the oldest journals in geology, The Journal of Geology (JG) has since 1893 promoted the systematic philosophical and fundamental study of geology. JG publishes original research across a broad range of subfields in geology, including geophysics, geochemistry, sedimentology, geomorphology, petrology, plate tectonics, volcanology, structural geology, mineralogy, and planetary sciences. Many of its articles have wide appeal for geologists, present research of topical relevance, and offer new geological insights through the application of innovative approaches and methods.
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The Journal of Geology
© 1986 The University of Chicago Press
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