Everyone appears to be busy posting Geopuzzles, Friday Field Fotos 1and 2 or Airliner Chronicles. Today I felt like posting something interesting to bother you with, too. Blogging is quite a long way down my lists of priorities, meaning I really got a lot of useful stuff done in the last days. Here is a foto of a sample outcropping right on my bookshelf. I am curious who can tell me what it is and how it forms. No need to write an essay though - we are not working here, right?!