What with the Kingston Trio, Joan Baez and Judy Collins performing in the area recently, maybe the times are a-changin'--or at least reversin'. Last night at the Merriweather Post Pavilion, Peter, Paul and Mary rekindled memories of the '60s by trading in nostalgia, sentiment, humor, politics and, most of all, beautifully crafted harmonies.

While those harmonies have grown darker over the years, they are no less affecting now. The trio developed lovely, often delicate contrapuntal lines, staggering their voices over the simple but solid guitar and bass accompaniment. They also took turns singing lead, gracefully complementing each other during the usual parade of hits as well as on Phil Ochs' "There but for Fortune," which they dedicated to the late Harry Chapin. Of their brief solo spots, Peter Yarrow's version of Bob Dylan's "I Shall Be Released," which inspired the crowd to chime in magnificently, was clearly the highlight.

As Noel Paul Stookey rather bluntly pointed out ("some hardhearted reviewer out there is going to call this ballad cloying . . . "), sentiment runs deep at a Peter, Paul and Mary concert. Though not all of their songs cast in this light possess the perennial charm of "Puff the Magic Dragon," the worst of them constituted harmless filler well sung.