Mount Zion refers to an Orthodox Jewish cemetery in Queens, New York, built in 1893, sandwiched between a New York City Sanitation plant and the Long Island Expressway. ''Sepulchral portraits'' refer to miniature photographs once placed on many of Mount Zion's tombstones, a custom brought over by Jewish immigrants from Eastern Europe. These images--often heavily retouched--were burned onto porcelain or metal tablets, and then glazed. The process was, at the time, advertised as permanent; but the ravages of the elements, pollution, and vandals have transformed these portraits into something else altogether. What remains of them--and what has become of them--is what John Yang has set out to portray in his own series of photographs, taken between 1994 and 1998. The result is a fiercely moving document, a meditation on morality, memory, the urban landscape, and the photographic process. Much like his subject matter, Yang's photographs are themselves memorials--to Mount Zion, to its urban environment, to its occupants, to the gesture of its sepulchral portraits, and to photography itself.