Check out fitz's reply above for other examples - apparently there are several others around the white sea coast.

it's a bit diffiicult to know all the details of dating as we're reliant on Alex's translations. The most recent and definitive work is Alexander Martynov’s book “Ancient trails of Solovetsky Islands”. Martynov is the resident beleagured Archaeo who has lived on the islands since 1978.

After Vinogadov, most of the research and analysis was done by a Professor Kuratov. The labyrinths are linked within a complex of funerary monuments - cairns, dolmens, graves and are associated with burial remains found over the last eighty years.

The damage was probably done during the establishment of the gulag - either institutional vandalism or for the purposes of plundering building materials. I think the reference to their removal is to do with the relatively small size and portabilty of individual stones rather than through natural weathering