Select the 'flat' parts of a waste rock dump and get the surface areas.
I need the 3D surface area of the 'flat' portion of a waste rock dump (top of lifts), and the 'slope' 3D areas. I am sure that previously I have selected the flat areas of a waste rock dump (between lifts) from my gridded DEM using something like, 'select areas with same elevation' and then get the area of this selection. I then subtracted the flat area from the total area to get the 'slope' area. I can't seem to find it any more! How did I manage this last time?