Sloughing

I couldn’t help noticing these two parallel lines running up the trunk of this tree.

You can see they start at the base and the left one stops after almost two metres

The other runs in on for at least another two metres.
Perfectly parallel, they almost look as if they have been machined. 

It could be a case of “frost crack”; alternate freezing and thawing.
Or perhaps the trunk has outgrown the bark and is sloughing like a snake?