As some have already commented, ERs can somehow trigger memories.
All this talk of rocks, spectrometry and geology hammers reminded me that this afternoon we visited White Scar caves under Ingleborough in the Yorkshire Dales. A very interesting tour was had and if you have never seen a cave system or stalac-wotsits before it is well well worth a visit. Of course, just a few miles up the road is Ribblehead Viaduct so an enjoyable late afternoon walk under the viaduct and up to Blea Moor followed.