Both are heads. Literally. The word remains in English as a cob, known in cobblestones (each has a round head) or a cape, which is also a headland, and that’s the Icelandic word: hæð, or head, or height. Remember that for the culture that settled this magical place, these really were heads. And so they remain.
Some farms in Iceland are in the most marginal patches of grass in the midst of lava fields. Here’s Thor’s Shield, the mother of all shield volcanoes, at the peak of the Mid-Atlantic Ridge, where it crashes into land underfoot. There’s a little bit of grass here in Thingveillir, but not much.
Lots of wind, though, which makes it a great place to take some of that grass and build a house.
Beautiful, isn’t it. Every farm in the country has ruins of turf houses like this. That’s the thing about Icelandic views: it’s the fact that people live on this land that makes it beautiful. The hard work of warming the land has been done. After all, the story here is one of settlement, not of conquest.