Let's look at the map.
2 seconds sound clip from the Back to the Future Part III movie soundboard.
You can hear this line at 00:10:24.197 in the DVD version of the movie.
Quote context
[...]
- Your friend in time, Doc Emmett L. Brown. September 1st, 1885.
- I never knew I could write anything so touching.
- I know. I know, Doc. It's beautiful.
- It's all right, Copernicus. Everything is gonna be fine.
- I'm sorry, Doc. It's all my fault you're stuck back there. I never should've let Biff get to me.
- All right, according to this, the time vehicle is sealed off in a side tunnel.
- Whoa! I think you woke up the dead with that blast.
- Take this camera. I want to document everything!
[...]