[Tagging] What about a disused quarry and historic surface mining?

[ksg]

> Am 10.01.2017 um 00:04 schrieb Tom Pfeifer <t.pfeifer at computer.org>:
> 
> They consist of the remaining geological material, which is of natural origin.

For the remaining exposed rock we use mainly natural=bare_rock.

> 
> There is a geological cycle as well, with mountains moving up and down, continents sink or lift up...
> 
> I would not be so picky and allow the new cliff to be called natural, while I associate other purposes with an embankment.


Due to my professional background I have to be precise here ;)

Steep natural rock faces are formed primarily by tectonic uplift and subsequent weathering and erosion or during the ice ages by glacial erosion. 

Artificial rock faces in quarries and open pit mines, called berms, are created due to blasting. The faces are typically inclined 60-70° with drops of max. a few tenth of meters. This fundamental difference might be best taken into account by using man_made=embankment for these.