 Van Tassel held weekly channeling sessions at Giant Rock at which people could "ask questions" and "channel answers" from extraterrestrials.According to Jerome Clark, these gatherings coalesced the scattered contactee subculture into a recognisable movement in January 1952.This led to the annual Giant Rock Spacecraft Convention organized by Van Tassel, which began in the spring of 1953 and continued for at least another 24 years.