So how do glitches randomly grow bridges?
Because it's a glitch!
What you see there is actually a river in real life with a bridge in real life, however by accident the river turned out to be a deep canyon and the bridge stayed with it. This has to do with elevation data error and can be easily corrected.
I guarantee that that hole in TX is an "easter egg", that is, something the programmers just throw in to see if people find it. I figure programmers have to have fun somehow.
No, it's not an easter egg. Easter eggs are things like the Aurora Borealis, and Kilauea in Hawaii erupting. It's been confirmed that it's a glitch and there are a couple others like it.
There are patches at Flightsim.com that fix them and there is a rumor that Microsoft is working a patch to fix these glitches along with some other bugs.
"Generosity is giving more than you can, and pride is taking less than you need." - Khalil Gibran