Which sentence is more formal?

 - Dr. Atkinson and her team took horses and went to a place that had no modern medical services.
 - Dr. Atkinson and her team traveled by horseback to a remote village that had no modern medical services.
The second sentence is less formal. You can tell because it uses overly simple or imprecise language (took, went).
The first sentence uses more precise language, so it is more formal overall.