Ironstone wall

The Upper Blue Mountains has a lot of ironstone in the ground which can be a nuisance when gardening, but also provides a ready supply of material for building dry stone walls. These are quite common in the area, many over 100 years old, but the art survives to this day as evidenced by the base for this modern sign.

The prevalence of ironstone, together with the high altitude of the area, also means that we are very vulnerable to lightning strikes. A few years ago we had an almost direct hit on our house which completely crystalised the main switch on our electricity meter board, and took out a few electronic appliances. 
Surge protectors can only do so much, so we now carefully monitor the lightning strike app on our phones and madly rush around unplugging appliances when we get a "red alert" warning.