| Summary: | This paper describes large steps developed in sandstones of the Jurassic Bug Creek Formation on a 5 km long plateau in the Richardson Mountains, Northwest Territories, Canada. Except for the steps atop the plateau, the planar portion or tread of each step abuts a riser or a scarp at its upper end and a block barricade at its lower end. The weathering of bedrock and blocks supplies fine sediments that cover the surface of the treads. The thickness of the surficial cover appears to be less than 120 cm. According to nine 14C dates, the sediments are Holocene in age. This study stresses two features of the giant steps: subterranean drainage and the presence of block barricades. It is proposed: (1) that subterranean drainage plays an important role in the preservation of block barricades; and (2) that the giant steps can evolve into cryoplanation terraces if the block barricades are destroyed by erosion. Copyright © 2006 John Wiley & Sons, Ltd.
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