Geology is cool. At this very moment I sit atop a layer of Silurian dolomite which is so hard, it gave the glaciers a run for their money.  This layer exists in the UK too I think(??!), but most of it is in the US.  This formation is probably more famous for the water that runs over it: Niagara Falls in NY.  It dishes down under the Great Lakes and Michigan, and comes to the surface again, forming the "thumb" on the coast of WI.  Arguably the whole state is an unconformity, but mostly just in the sense that the glacial till deposited on top of the bedrock is far, far newer than everything that got eroded.  (The geology here in WI is otherwise quite boring, mostly being of that age -- everything newer's been worn away by glacier or erosion.  Though there was that one time, a couple billion years ago when the Keweenawan Rift formed, bringing famous native copper deposits to the U.P.)<br><br>Geology is also the only topic I fell asleep to, reading in the library.  It wasn't even a boring topic, it was about an ancient crater impact!  Well, it's complicated, I guess. :)