What is also interesting is that the area is near the non-magnetic south pole. The geomagnetic field line are vertical rather than lying across the planet from pole to pole. This area creates a void where compasses don’t work.
No one seems to have a real theory about how this block landed on and continues to float around on this iceberg yet. It is definitely baffling.
Learn Something Fun: The word iceberg comes from the Dutch ijsberg which means "ice hill".
Compasses work just fine there as earths magnetic field is not limited to the actual planet.
The block is resting on level surface without any sinking into the ice below, so it has not been there for very long. It has never been "inside" the ice as the melt would have been uneven...
That piece of wood has most likely been put there by the photographer or someone is playing a trick on him/her. Sheesh.