San Diego-based Geary Interactive, a digital marketing agency, said Monday that it has acquired Fathom Online, a search engine marketing and technology services firm. Financial terms of the deal were not disclosed. Fathom Online is based in San Francisco, and was started in 2002; the firm is venture backed by Constellation Ventures. According to Geary Interactive, Liza Boyd of Constellation Ventures will assume a seat on the board of directors of Geary Interactive. Fathom Online's Steve Gillan will serve as CFO of Geary; Mihir Choudhary will become CTO and VP of Engineering, and Jinenne Sutherland will serve as reach director at Geary as part of the acquisition.