Mysterious Hole in Frenchmans Cap

Hi all - I took this photo during a 1983 trip to Frenchmans Cap. The grainy old shot shows a "hole" through Frenchmans Cap, somewhere near the summit. I remember thinking at the time: "Is that a lake? No ... it's actually an arch/hole going right through the mountain!"
I was back on Frenchmans again a few weeks ago - 31 years after my first trip - but I didn't find this spot again. Sure the weather was less than perfect, and I didn't look very hard. But my memory of the 1983 walk was that the track to the summit went right by this "hole". I guess the current route doesn't follow the old route. Has anyone else here seen this feature? If it weren't for the photo, I'd be tempted to think my memory was faulty. What light can anyone shed on this?
cheers
Peter