Shatter cones are conical fractures present in rocks. The shatter cones at Sudbury are clearly seen in the Huronian quartzites. These were first correctly identified by an American geologist, Robert Dietz, in 1964. He pointed out that they likely originated by intense shocking of the rock from a meteorite or asteroid impact. The Sudbury features range in size from several metres to a few centimetres. The one in the centre of the picture is about 1m. The impact hypothesis for Sudbury is supported by melt breccias and shocked mineral grains.
Sudbury is not the only place in the world that you can see such features and we point you to several web sites that you can investigate to find out more about these enigmatic structures.
Vredefort Shatter Cones (Africa)
Beaverhead structure, Montana
http://www.lpi.usra.edu/ (the Lunar and Planetary Institute)
http://miac.uqac.uquebec.ca (the Meteorites and Impacts Advisory Committee to the Canadian Space Agency, alias MIAC)