A GEOLOGIC STONEHENGE: LE PARC DES GALETS

In 2005 we created an outdoor exhibit of large rock slabs outside of the Musee Quebecois D’Archeologie at Pointe du Buisson. The exhibit is composed of boulder-sized specimens of silica-cemented sandstone of the Cambrian Potsdam Group. The sandstones bear primary sedimentary structures such as wave- and current-ripples, adhesion structures, desiccation cracks, raindrop imprints, and load casts. They contain trails, trackways, and steinkerns of some of the first animals to crawl onto land, and imprints of the largest known Cambrian animal. Slabs are arranged in a horseshoe pattern and interspersed with small shrubs and trees that give the exhibit a garden-like feel; visitors walk around a small garden loop in which they are bordered by slabs on both sides. The exhibit is self-guided, free, touchable, accessible both when the museum is open and when it is closed, and slabs have permanently affixed labels which are at a height and in language accessible to children and adults. The exhibit is popular, even in winter when partially covered in snow. Children may climb on some of the slabs and visitors can sit atop nearby bench-shaped slabs.

The rocks in Parc des Galets are a catalyst for informal science education in this region because visitors can use them to explore environments in deep time, and to learn that the surface of the earth was not always as it is today. For example, visitors in the exhibit are drawn toward relating the primary sedimentary structures visible on the rock slabs to specific environments they are familiar with (e.g., polygonal mud cracks with desiccation of mud on tidal flats or ponds), and they cannot help but observe the fossil trackways that cross-cut these structures. These relationships foster interpretation of the slabs – allowing not only visualization of the animals that made these traces, but linking of the activities of these animals to specific environments in deep time.

Potsdam strata are visible throughout this region and since opening of this museum exhibit, additional occurrences of these fossils and facies have been discovered by members of the local community. Following on the heels of some of these new occurrences, in 2009 an indoor hall (the Hans J. Hofmann Hall) displaying additional Potsdam fossils and structures was constructed, and is currently being integrated with the outdoor exhibit.