The Dangers of Mountain Biking

I had an action-packed morning. Got up early, packed my bike up and went out to the trails at Lake Grapevine in the DFW area. I was riding along, and came to a rocky dropoff on the trail about a mile or so in, and a guy (probably mid to late 40's) was sitting off to the side of the trail at the bottom of the dropoff, his bike just laying in the trail at the base.