Bung:JeremyNzl:If the cable is not rated for direct burial it should be in conduit.
If the cable was taken anywhere near a fence an old style marker used to be a short piece of the conduit screwed to the fence.
Sadly while that seems like a great idea, no sign of any marker. Given some of the electrical work on our house defies any logic and demonstrates no thought whatsoever was put in by the sparkie, a small helpful gesture such as this was probably well beyond them.