Brian "Geologist" Weitz is a "member" of Baltimore-based group Animal Collective. His main contributions to the group are
absolutely nothing in the form of sound manipulations and noises. This role has changed much during their career. Initially, he operated MiniDisc Players and created the noise of their harsh noise laden Danse Manatee and Hollinndagain. In their more recent albums his instruments of choice are samplers and effects processors. Over the years, his role as the "noise man" of the band has added at least some substance to their albums, such as Strawberry Jam and Centipede Hz.
Like Avey Tare and Panda Bear, Geologist wore somewhat of a costume during the early touring days of Animal Collective, which in his case was a headlamp. After the two other members decided that they didn't need costumes to preform comfortably, they pressured Geologist to stop using the head headlamp onto stage stating it was "fucking gay". To this day Geologist still wears the gay flashlight due to poor eye-sight.
His only songwriting contribution to the band is a solo track found on the Keep EP called "Jailhouse." He has also created the soundtrack tho a short film named Man O War.