Does Iceland belong to Europe or America, geologically?

Answer

The whole question was:

Since Iceland is between the continental plates does it then belong neither to Europe nor America, geologically speaking?

It would be more correct to say that Iceland is at the meeting point of the Eurasian and the American plates and hence belongs to both of them, the eastern part to Europe and the western part to America.

Regarding other natural conditions Iceland has more in common with Europe than America. The flora is more similar to the European one, perhaps partly by influence from the human settlement coming from that side.

There were only very few species of wild mammals here at the time of settlement 1100 years ago. The most important one is the polar fox which is found in a great area all around the North Pole of the earth. But its, for instance, noticeable that the polar bear does not live here as it does in Greenland and Canada. This is thought to be connected to its dependence on sea ice for obtaining its main food, the seals.

Icelandic bird life is much more related to Europe than America. Among bird species coming from the western hemisphere we may, however, mention the Northern Diver (l. Gavia immer) and the Harlequin Duck (l. Histrionicus histrionicus).

This difference in flora and fauna derives from the fact that the climate in Iceland is "European", so to speak. The climate at similar latitude on the American East coast is quite different from Iceland and the western part of the European continent, lying to the east from us. The winters are much more tough in the west, the summers warmer but, still, the average temperature of the year is lower. This difference is of course caused by the Gulf Stream and the dominating southwestern winds. The Old Norse Wineland seafares really did notice the anomaly of the weather relative to the latitude, as can be seen from the Winland sagas. But, anyhow, it is thus not without reason that the line between America and Europe is usually drawn between Iceland and Greenland, the latter being on the other hand much more similar to the western lands.

This conclusion is further amplified by the fact that the people most related to us are found on the European side. But perhaps this kinship is not stronger than the one between certain areas of America on the one hand and European areas on the other hand. As an example we can take the inhabitants of New-England and Britain or Quebec and France in the 17th-18th century.