Four months’ field work in New Mexico and Arizona, in 1906,2 resulted in numerous geologic sections and fossil collections. Some of these results have been published.3

The present paper presents some Upper Permian and Lower Triassic? sections, with their faunas as represented in our collections. The faunas are mainly from the upper Kaibab and lower Moenkopi formations.

Northern Arizona represents an old peneplained surface, developed with a slope to the south, which was raised into a plateau during the Pliocene. Since that time the softer Triassic ? shales have been largely eroded, leaving exposed the hard, siliceous Upper Permian (Kaibab) limestones. This erosion brought into relief old fault lines, and, with the aid of subsequent faulting along some old and many new lines, has produced the present topography. These strata, very nearly horizontal, have usually a gentle dip to the north; this is true from the southern edge of the . . .

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