The Geology and Petrography of Crater Lake National Park, 1902
Union Peak (elevation 7,881 feet.) is on the summit of the Cascade Range, in Oregon, about 50 miles north of the California line and 8 miles southwest of Crater Lake. It is a sharp, conical peak (Pl. III, A) rising about 1,400 feet above the general level of the crest of the range. About the base upon the east and west sides, as well as upon its summit, are remnants of the original tuff cone, but the mass of the peak exposed on all sides is of solid lava. The molten material did not sink away after the final eruption. The volcanic neck resulted from the cooling of lava within the cinder-cone in the top of the volcanic chimney. Union Peak to-day shows us the neck stripped of its cinder-cone.
Plate III.—A. UNION PEAK