We went to #MountSunday today (aka #Edoras) & while @ShayneParkinson was taking pics of the view, I was looking at the rocks (warning: I am not a geologist). The mountain seems to be granite with clear marks of ancient ice smoothing it (2nd pic). On top of that is soil that looks like loess, formed from dust carried by the wind. Braided river channels, which surround the place, are a good source of dust, and we all know it gets windy. Remember that flag?