Seeing this word triggered a memory from long ago.
I am referring to those potholes in soft rock that are caused by the grinding action of harder rocks as they are twisted by the action of flowing water.
It was in the Adelong region of NSW. I spotted a substantial pothole about 35 centimetres wide and of considerable depth. It was half full of water.
Hoping that if I bailed it out I would find gold I approached the hole and was surprised to find a platypus which immediately dived when it saw me. The beast had obviously blundered into the pothole the vertical sides of which prohibited escape. I wasn't going to reach in to try to rescue it because I had heard that male platypuses have poison spurs on their back legs and that the poison was similar to that of the black snake.
I hunted round until I found a log which could be inserted into the pothole at an angle so that it formed an escape ramp. I eased the log into the pothole, not wanting to pin the platypus to the bottom and went away to continue panning.
I returned after a while and saw that the log, which had been dry when I put it in the hole, was now wet with fragments of weed here and there so it appeared obvious that the platypus had made use of the ramp and escaped from that lethal pothole.
I didn't pan a lot of gold that day yet it remains one of my more satisfying memories.