Shatter cone

Shatter cones are rare geological features that are only known to form in the bedrock beneath meteorite impact craters or underground nuclear explosions.

[2] In finer-grained rocks such as limestone, they form an easily recognizable "horsetail" pattern with thin grooves (striae).

Coarser grained rocks tend to yield less well developed shatter cones, which may be difficult to distinguish from other geological formations such as slickensides.

The largest known shatter cone in the world (more than 10 metres in length) is located at the Slate Islands in Terrace Bay, Ontario, Canada.

The azimuths of the cones' axes typically radiate outwards from the point of impact, with the cones pointing upwards and toward the center of the impact crater, although the orientations of some of the rocks have been changed by post-cratering geological processes at the site.