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Description: This boulder was dropped here between 12000-18000 years ago as the continental ice sheets once covering most of Canada were receding. These large boulders left behind are referred to as ‘erratics’. This boulder displays beds of slate and quartzite, which represent the metamorphic equivalents of shale and sandstone, respectively. You will notice that the beds of slate appear as though they split into flat sheets. This rock fabric is referred to as ‘rock cleavage’, or ‘slatey cleavage’ and results from the alignment of small, flat mica mineral grains aligning with one another under the influence of metamorphic pressure. You will not observe this fabric in the quartzite beds since these beds are dominated by more rounded quartz grains rather than mica.