Abstract

MODERN TECHNIQUES IN THE STUDY OF TERTIARY CONTINENTAL SEDIMENTS

BY JOHN CLARK

Early stratigraphic work in Tertiary formations was limited to faunal correlation and brief, macroscopic description of the sediments. During the past 20 years, various students have developed special techniques which have yielded valuable results.

Most useful petrologic data are: (1) Quartz-feldspar ratios; (2) nature, amount, and factors controlling the cementing material; (3) color, provided that the factors controlling it can be determined; (4) nature of the heavy minerals; (5) gradations in maximum grain size. Special methods of sampling are necessary in order to obtain uniform results.

Paleogeographic interpretation must at all times accompany faunal and petrologic studies. Local variation in facies is so extreme that without determination of the environment of deposition, correlation and interpretation become impossible.

FUNCTION OF THE FORELEG IN AMPHIBIAN LOCOMOTION

BY F. GAYNOR EVANS

Experiments with Amblystoma opacum indicate that the forelegs play a . . .

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