As currently used, systems theory is lacking a universally agreed upon definition. The purpose of this paper is to offer a resolution by articulating a formal definition of systems theory. This definition is presented as a unified group of specific propositions which are brought together by way of an axiom set to form a system construct: systems theory. This construct affords systems practitioners and theoreticians with a prescriptive set of axioms by which a system must operate; conversely, any set of entities identified as a system may be characterized by this set of axioms. Given its multidisciplinary theoretical foundation and discipline-agnostic framework, systems theory, as it is presented here, is posited as a general approach to understanding system behavior.

Upper Pleistocene rhyolitic ash-flow and air-fall tuffs, erupted from several centers, were sampled in 23 pumice-filled basins over an area of 16,000 km 2 . Fifty pumice-matrix samples were analyzed for as many as 20 trace elements. Ba, Fe, Hf, Rb, Sm, Sr, Th, Ti, and Zr were particularly useful in "fingerprinting" correlations between basins and in corroborating the stratigraphy previously established within individual basins.

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In 1970, Johns Hopkins University produced the first Indiana Amish directory. Its goals were narrowly related to genetic research, and it opened a window into a nearly complete census of this settlement. It is rare in social science to have such a complete picture of any population. A decade later, the second directory was published. The Amish decided to put their own energy into producing this compendium of birth dates, family size, district maps, and detailed information on the ministerial history of the settlement.       Using the data from eight directories, we can provide a nearly complete analysis of demographic change in the third largest Amish settlement in the world. In this study, we look at growth in settlement size, changes in family size, migration in and out of the settlement, defection and retention of Amish young people, the growth in nonfarm occupations over time, and the frequency of prominent family names.

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