(top circle=where I came off the wall; next circle is piece that held, Metolius #7; third circle is belayer; fourth circle is where I arrested)
I had 30 meters of rope out between the belayer and myself. I fell, ripping out a piece I knew full well would not hold, I was off route and it was run out into the 5.10 range when a clay foot feature on a mostly featureless wall gave way. I was over the roof of the 2nd pitch and the accelerated fall then ripped out a #8 Metolius (corner of one cam is sheared) that was definitely in the green zone in a significant crack and another piece or two down to a #7 cam that held. My total fall was 40 meters, I was arrested 10 meters from the base of the climb itself. I had fallen below the belay ledge.
I can't recall with 100% certainty what I had in below the #8 Metolius. However, I am interested in the failure of this piece. When placing it, I was not positive what the route did after I finished the corner and turned the roof to the right. I placed it for a vertical fall. In reality, I moved into another corner to the right that would have placed me maybe 1.5 meters off center to the right of the corner and about 3-4 meters above the #8. That corner offered little if any protection and the 00 I did place had no expectations from me. I noticed that most of the rock on Watch Tower had a high concentration of clay.
Scared as I was, in the end I was amazed at the system and how well it worked and how little injury I incurred. Of course I could have decked on the belay ledge, or chock stone in the chimney below it.
Watch Tower, West Face, Alpine II, 5.7, Yoho National Park, Canadian Rockies, July 28, 2006.