A nice example can be admired in the Tensha-en garden in Uwajima, where some of rocks were assembled to create a path and a bridge, while others, the stone arrangement on the lake shore, were fitted to prevent erosion. Other rocks, like the one in the foreground of this photo, are there just as ornaments...
EXIF info:
Nikon Df
Lens: 14mm F/2.8D
Focal Length: 14mm
Aperture: F/7.1
Shutter Speed: 1/320s
ISO Sensitivity: ISO 500