[granite example](https://images.app.goo.gl/ppnv9j5wbXxdyCBe7)
[glass example](https://images.app.goo.gl/nTdBaCE52u7UiC2S7)
In: 2
Sometimes ripples occur just below a [bulb of percussion](https://forums.arrowheads.com/forum/general-discussion-gc5/artifact-questions-answers-gc9/37645-bulbs-of-percussion). Energy radiates from an impact and forms a shear plane. The shear plane after the bulb is usually smooth but sometimes it ripples. The ripples are caused by deviation along weak planes slightly out of line with the shear force, but then auto-correct back to the main shear.
Granite does NOT typically ripple in the same way at all. The granite shown is rippled because the granite was drilled and pre-cracked along the main plane. It also deviated in weak directions and corrected back to the pre-cracks. The main difference is that it involved multiple blows.
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