Ruined stone huts in the bush

A few months ago the RFS did a controlled burn in bushland on Middle Harbour River behind East Lindfield. Not long afterwards while running the trails I happened to glance up the hill into the recently burnt bush and saw what looked like man made stone walls about 20 metres from the trail. I went up to have a look and it turned out to be the ruins of several stone huts! I’ve passed by that place countless times but never knew what was hiding so close. It was only after the fire had burnt away the scrub that it became visible from the main track.