TEARDROP PARK     Between Warren Street and Murray Street, east of River Terrace.   Designed by innovative landscape architect Michael Van Valkenberg, two-acre Teardrop Park brings a little of the dramatic Hudson River Valley to Battery Park City. Located between Warren and Murray Streets, River Terrace and North End Avenue, Teardrop features a magnificent "Ice Wall," artwork by Ann Hamilton and Michael Mercil, a children's slide, sand boxes, water play, a reading area with rock seats, places to "rock hop," naturalistic plantings, and much, much more for park lovers to discover.