The Bras d’Or Lake Biosphere typifies all the varieties of karst present over Cape Breton Island; developed in limestone, gypsum, marble and salt diapirs. Approximately 23% (2700 km2) of Cape Breton Island consists of a wide variety of glaciated bedrock which has the potential for karst formation. An additional 1100 km2 has been inundated by post-glacial sea level rise. These include meta-carbonates, carbonates and evaporites which have undergone three main episodes of karstification. The Island represents a portion of the tectonically ancient, deep crustal, eroded terrain of the Appalachian Orogen, more recently influenced by the interplay of sea level change, ice sheet stability, transient ice aquifers, climate change and isostatic rebound. Lowland karst units are generally characterized by broad scale, till covered, thick evaporite sequences. Within this zone are found solution trenches near basin boundaries, salt diapirs and extensive foundering zones due to salt dissolution, which allowed development of karst breccias to depths exceeding 300 m. The presence of localized salt springs suggests a process to move saline water up from depth through foundering breccias or hydraulically active faults. This may in part be responsible for deep submarine trenches developed to depths of -260 m.  Mountain flanks incorporate hydraulically active faults which have deformed evaporite and carbonate sequences along basin margins. The highlands expose paleo karst features within marbles, covered with a thin, discontinuous glacial cover. (by Fred Baechler)

UNESCO MAB WNBR database file

Bras d’Or Lake Biosphere Reserve Association