@albertcardona is there a chance that they are very mountainous continents that just also happen to be covered in ice?

@albertcardona Crustal thickness not only varies as a response to modern montain building processes, but it can also be related to suture zones of long-gone continental buildup processes (as it's probably the case here), cratons that have been cooling since Proterozoic times (those in Africa, for example) and complex mantle processes

@albertcardona From what I understand, continental crust thickness isn't a predictor of mountain height per se, but of average elevation underneath a given plate. The Antarctic Plateau is the largest of its kind in the world, with an average elevation of ~3000m, presumably due to the continental crust thickness you can see in that map.