On December 29, 2012 I was looking at the winter erosion effect on the First Nations Burial Cairns. On the largest  Cairn, three concrete rings appeared which have never shown up before, since they have been covered with vegetation.

Here is the 2011 version of the mound:

Burial Cairn in 2011

And below are the concrete rings after heavy geese grazing and erosion has bared the top of the mound: Currently we can only guess that they were added since construction of the lighthouse and were perhaps used as a marker or base for an antenna.