Thats not the point. The point is that Quincy's underground data center would be a backup for Chicago, KC, or St Louis's if they ever got hit with a dirty bomb. The fact that its a cave just means that Google wouldn't have to invest millions of dollars to create a hardened data center, because it does that naturally.

These caves don't flood. Monster food companies use them to store food in, and they are a mile from the river.

It's great that we can apply mother nature in all her glory to present and future technologies, and that they can work in harmony with each other. Google should really consider Quincy to demonstrate this new "Green" idea.