Thanks for all the comments, everybody.
Yes, Iceland is amazing, and my 1974 visit was quite memorable.
Even if now volcano is currently erupting while you are there, the evidence is all around. Near the base of Hekla, for example, you can easily distinguish recent ash from that of earlier eruptions, where lichen and whatever have started growing.
My understanding is that 1974, when I was there, was the year they first completed the "Ring Road" that goes all the way around the island. My wife and I spent two weeks with a hiking club in the south, and then we flew to Akureyri in the north, where we rented a VW bug to explore places like Myvatn on our own.