Question: On what date did the 1980 eruption of Mount St. Helens, in which "Crater Glacier" was formed, occur?
Sentence (from "1980 eruption of Mount St. Helens"): On May 18, 1980, a major volcanic eruption occurred at Mount St. Helens, a volcano located in Skamania County, in the state of Washington, United States.
Relevant evidence: Yes