Geological Survey Professional Paper 554—D Cenozoic Volcanic Rocks of the Devils Postpile Quadrangle, Eastern Sierra Nevada California

FRONTISPIECE. Photograph showing well-developed columnar jointing in andesite at the Devils Postpile.

PLATE

FIGURE

1. Index map of the Devils Postpile quadrangle

2. Variation diagram of the Mammoth Lakes volcanic suite showing classification according to the "alkali-lime index"

3. "Differentiation trend" diagram for the Mammoth Lakes volcanic suite

4. Silica—refractive-index diagram for volcanic rocks of the Mammoth Lakes area

5. Diagram showing range in percentage of silica of some of the mapped volcanic units as inferred from refractive indices of fused samples

6. Photograph of basal part of quartz latite of Two Teats on east side of San Joaquin Mountain

7, 8. Photomicrographs of tuff of Reds Meadow—
7. Lower flow unit
8. Upper flow unit

9. West-east section in vicinity of Rainbow Falls showing reconstructed surface of the tuff of Reds Meadow

10—13. Photographs of—
10. Polygonal joint pattern displayed by tops of columns in the Devils Postpile
11. Northernmost of the two Red Cones as viewed from the southern cone
12. Rhyolite dome south of Deadman Creek as seen from Deer Mountain
13. Upper surface of rhyolite dome south of Glass Creek showing typical irregular blocky surface

14. Vertical aerial photographs of Deer Mountain area, mounted as a stereopair

15. Photograph showing view of Inyo Craters from Deer Mountain

TABLE

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UNITED STATES DEPARTMENT OF THE INTERIOR
STEWART L. UDALL, Secretary

GEOLOGICAL SURVEY
William T. Pecora, Directory

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