Fluxus artist Ben Patterson’s latest exploration, reconstituted as an installation in cast concrete and flowing water, traces a small and crucial phenomenon on the earth’s surface: the Los Angeles River. Patterson recapitulates the course of the river through our urban environment in five grooved slabs, each elliptically documenting a stretch of the stream with photos and words. The words, pressed into the concrete itself, capture impressions at each site, while the books of photos chart without judgment the presence of man and nature. Patterson enjoys ironic moments where nature’s presence is actually man’s (e.g., in a metal gate with cutout animal silhouettes); but he enjoys still more the simple fact that a city’s first armature is always a river. Solway Jones, 5377 Wilshire Blvd., L.A.; Tues.-Sat., 11 a.m.-6 p.m.; thru Aug. 12. (323) 937-7354.