Perched erratic boulder, North West Territories, Canada. This large granite boulder is resting above glacially rounded bedrock. The large boulder was positioned when an ice sheet carrying rocks eventually melted. Then, the debris within the melting glacier settled out, placing the large on top of the smaller boulders.
— Source: Natural Resources Canada. Photograph by Lynda Dredge. Copyright Terrain Sciences Division, Geological Survey of Canada.

Perched erratic boulder, Newfoundland, Canada Blocks and boulders were deposited on this granite surface by melting glaciers, frequently in very unusual and precarious positions.
—Source: Natural Resources Canada. Unattributed photograph. Copyright Terrain Sciences Division, Geological Survey of Canada.

Erratic boulder, northeastern Manitoba, Canada. A sense of the size of the large erratic block can be estimated noting the person standing in front of the block, on the left side. The plain that the block is resting on is covered with boulders carried by the Keewatian Ice Sheet.
—Source:Natural Resources Canada. Photograph by Lynda Dredge. Copyright Terrain Sciences Division, Geological Survey of Canada.

Erratic boulder, northeastern Manitoba, Canada. Glaciers that once covered this plain, scoured away the landscape leaving only solid granite rock.Very little till remained, although boulders, carried by glaciers, were placed on the granite surface.
—Source: Natural Resources Canada. Photograph by Lynda Dredge. Copyright Terrain Sciences Division, Geological Survey of Canada.