Evarts et al. (2009) assign Rocky Butte an age younger than 500,000 years. One Argon-argon dating experiment determined an age for Rocky Butte lava of 285,000 years ± 16,000 years ago, which matches the normal magnetic polarity for the lava deposits at the Butte. There is a magnetic anomaly about northwest from Rocky Butte in Portland, but it is unlikely to be associated with the volcano or the Boring Lava Field in general. Local newspaper sources report that Rocky Butte is extinct.