Precisely made limestone fences - From the Totara Estate days of the mid- late 1870s.
The rock underlying most of Totara Estate land in the Totara Block is limestone of about 23,000,000 yeas age - the topsoil cover is generally quite thin and outcrops are everywhere. The stone for the walls will have been won from nearby as the wall was built - I can't imagine blocks were or would have needed to be carried more than a few metres!
As you can see from the exposed section, these are essentially drystone walls (there is a special name for walls built from lightly dressed fitted blocks but right now I cannot recall it) The walls have then been "bagged" that is plastered partly over the faces and in the cracks to even the surface. The treatment is both decorative and functional as it somewhat re-inforces the surface layers of stones as well as prenenting rain entry and the growth of weed plants etc which might otherwise establish. The stonemason/wallbuilder will drape a hessian or jute bag (such as one the burnt lime was delivered in) loosely over his hand and both fling and push mortar into the joints smoothing the resultant surface with the bag in one motion.