Single rope as in the 3000 foot one fixed to the ground?
Actually, our rope is 3,400 feet long. I'm afraid I don't understand your question. Our rope was secured at the bottom. All big wall rappels requires one to secure the rope at the bottom, otherwise the wind could send the rope flailing about all over the place. Not a safe practice to leave it unsecured.
behind the rappeller's purple backpack?
Nope. I don't know the name of that rock but look closely at the ground. Notice how the road is flanked by the large field? That's the fieled opposite from El Capitan. Timmy is on El Cap!
shot . Thanks for sharing . Cheers , Vahid .