(Table 1) Age determination of glass-samples from ODP Hole 135-841B

Several samples from the rhyolitic lavas encountered in Hole 841 B in the Tonga Forearc were made available by A. Ewart for potassiumargon (K-Ar) dating in an attempt to constrain the age of the eruptions. The material was supplied in crushed form and consisted primarily of volcanic glass together with some microphenocrysts made up mainly of plagioclase and quartz. Plagioclase could not be separated in sufficient amount for dating, especially as the potassium content of the plagioclase was quite low (~0.055% K). Petrographic examination of the volcanic glass indicated that it was remarkably fresh: it was clear, unaltered, and essentially isotopic. Thus, it was decided to attempt to date the volcanic glass.

Review: "Context : A framework for its Influence on Evaluation Practice (New Directions for Evaluation No. 135)" edited by Rog, D. J.; Fitzpatrick, J. L. and Conner, R. F.

This book offers a framework for the influence of context on evaluation practice and is applied to three case studies: environmental context; indigenous context and political context; and finishes with a process for implementation.

Sapientia, 1980, Vol. XXXV, nº 135 (número completo)

Contenido: El orden divino del hombre / Octavio N. Derisi – El fundamento de la metafísica tomista : el Esse e Intelligere divino, fundamento y causa de todos ser y entender participados / Octavio N. Derisi – Lógica y realidad / Gustavo E. Ponferrada – La lógica actual y la existencia de Dios / Adalberto F. Villecco – Versión subjetivista y realista de los llamados derechos subjetivos de la personalidad o esenciales del hombre / Rodolfo Luis Vigo (H.) – Notas y comentarios -- Bibliografía