Oblique aerial view of Mount St. Helens amphitheater as viewed from the north. Skamania County, Washington. 1980.

Album caption: Oblique aerial view of Mount St. Helens amphitheater as view from the north on July 22, 1980, sequence (9A-G) (photos nos. 17-23), showing the formation of pyroclastic density flow during the early part of the third eruptive pulse. A, 1900:59; B, 1901:03 PDT, timed photographs by the author; C, 1901:08 PDT, photo by Harry X. Glicken, time from comparison with at timed photograph that is not shown; D,E,F,G, untimed sequence taken within 30 seconds after C, by Harry X. Glicken. Skamania County, Washington. (See also MSH-July 22, 1980 nos. 69ct-75ct) Published as figure 9-F in U.S. Geological Survey. Professional paper 1335. 1986. Index card unavailable.