We live in a steep sided river valley in northern Portugal, and the place came with 5 Ha of woodland, on a SE facing slope.
We’ve only lived here some six months, and we’ve gradually realised that almost every square inch of the hillside has been terraced - the process is to build hefty walls along the contours, and then let the hill slump into the gap, making a level growing area.
The thought that occurred to me/thing I noticed was just how much IR the wall I was working next to was emitting after the sun went down - felt like a patio heater pointed towards my face from a few meters away. I then realised that the reason that they’re all so incredibly overgrown is likely the combination of thermal mass warming the surrounding area, water being forced to ground level at the foot of each wall, and accumulated mulch being trapped by each wall.
I can’t count the number of times since starting here that I’ve marvelled at the simple ingenuity applied towards working with nature, from the terraces creating a better growing environment than the now-farmed planes above us, to the positioning and orientation of the mill - it’s situated at the one point along the bank that gets sunlight all day, all year, apart from two weeks in midwinter - which just happens to coincide with an outcrop that they co-opted into a weir.
Anyway. I wonder to what extent the idea of a fruit wall stemmed from people seeing this sort of terracing, and deciding to do it without a hill.