Is this a run-on sentence?
Blood Falls in Antarctica's McMurdo Dry Valley gets its name from its famous crimson-colored water, which results from high concentrations of iron rusting as it comes into contact with the air.

 - no
 - yes
This is not a run-on sentence. It is not formed from two sentences that have been run together without appropriate punctuation.
Blood Falls in Antarctica's McMurdo Dry Valley gets its name from its famous crimson-colored water, which results from high concentrations of iron rusting as it comes into contact with the air.