Foxthought: Unconformity
In geology there’s a word for it: unconformity. A surface between rock layers where time is missing. Not eroded — not scraped away by some catastrophe — just absent. The lower layer was deposited, then the world did other things for a while, and then deposition resumed. Cut through the column and you can see it: Ordovician limestone sitting directly under Carboniferous sandstone with a hundred million years of nothing in between. ...