Tall Cairn, Red Slate Cairn, both 2004, and Pi Disc, 1989, installed in the side yard of the artist’s studio in South Portland. Tall Cairn includes stone retrieved from a sculpture project at Jackson Laboratories in Bar Harbor. Red Slate Cairn will be filled with slate from Sheldon Slate in Granville, New York. Pi Disc, made of cement and granite, was shown in Roberge’s solo exhibition at the Portland Museum of Art in 1989.