woolsack weathering
n.— «I now know that South Africa is, in part, one of the planet’s oldest continental fragments. I also have a name for the ageing process of those jumbled Karoo koppies—it’s called “woolsack weathering,” which is pretty obvious when you think about it.» —“Book Review: On the rocks” by Paul Ash The Times (Johannesburg, South Africa) Oct. 7, 2007. (source: Double-Tongued Dictionary)