Try to build a plateau like this in the screenshot. For creating it use the rectangle tool, where possible. Then select some of the tall grass just like that one in the screenshot and try to place it on the plateau. You’ll learn this is not possible. The tall grass of Inquisitor ground is below the regular grass of the Inquisitor outside’s plateau tiles.
Note:
The same goes for all the other ground tiles there. They cannot be used to build the plateau because the plateau’s regular grass tile is on a wrong layer.