THE Earth's surface exhibits faint circular patterns which have not been described before. These circles are characterised by near perfection of outline, by the presence of topographic highs (rims) along parts of their circumferences, by their generally large scale (diameters of from under 7 km up to approximately 700 km in the areas examined), and by their definition in various geological environments, in many rock types, and in rocks of all ages. Many of the circles are intermittent in places along their rims but about 55% of the approximately 1,170 definite circles observed to date can be visually traced around an entire 360° of arc. The circles are further characterised by the presence of fracturing and brecciation along parts of their rims and by the extraordinary control they place on regional geology in general and on ore mineralisation in particular.
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SAUL, J. Circular structures of large scale and great age on the Earth's surface. Nature 271, 345–349 (1978). https://doi.org/10.1038/271345a0
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