dominant grey colour, splotched occasionally with red, which gives the Cape Mountains their characteristic tint.
Very near the bottom there is in some places a well-marked band of deep-red slates, and towards the top a broader band of shales, slates, and slaty sandstones. The upper shale band, as it is called, is remarkable from its
Fig. 37. — Map of the south-western corner of Cape Colony, showing the trend lines of the folds and the area occupied by the great Karroo laccolite
being more easily weathered than the hard sandstones, and therefore it forms a conspicuous depression wherever it occurs, and is very useful in tracing the folds into which the series has been thrown. In the Cedar Mountains, on the western side of the Karroo, the upper shale band contains glaciated boulders, showing that icebergs must have been floating about in the sea in which the sediments were being laid down. Towards the top, but beneath the upper shale band, there are frequently found
