The paper is accompanied by a sketch map showing the main structural and orogenic features of the Canadian Shield. Three main types of structural patterns are distinguished. Regions characterized by high-grade metamorphism or granitic intrusions present swirling and circular structures of extremely complex pattern and relatively little topographic relief. Areas of low grade, folded Proterozoic rocks form linear belts of generally more pronounced relief. Areas of flat or gently folded cover rocks of Proterozoic age form broad sheets of low relief except where cut by diabase sills. The various types of structures found in the exposed Shield may be expected to continue beneath the Phanerozoic cover.

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