John Faithfull 🌍🇪🇺🏴🧡✊🏻✊🏿<p><span class="h-card" translate="no"><a href="https://mastodon.social/@JanPV" class="u-url mention" rel="nofollow noopener noreferrer" target="_blank">@<span>JanPV</span></a></span> Beautiful! Not my specialist area, but I think that these are hackle or plumose marks. Most rocks are not homogenous, so when fractures form, they propagate in rather complex ways. The ones in you photo look as though they might be associated with finer-grained (siltier, or more shaly) beds in the rock, and might have propogated downwards. I'm not a structural geologist so this is all a bit vague. <span class="h-card" translate="no"><a href="https://scicomm.xyz/@allochthonous" class="u-url mention" rel="nofollow noopener noreferrer" target="_blank">@<span>allochthonous</span></a></span> can probably say more, and more reliably! 😁 <a href="https://mastodon.scot/tags/StructuralGeology" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>StructuralGeology</span></a></p>