Trying to understand the geology of Lagavulin Bay

After a week of looking out at the view of Lagavulin Bay, it dawned on me that the sea must have worn through a ridge of hard rocks and then opened out a bay into softer rocks behind. The line of the harder rocks can be seen across the bay from Dunyvaig Castle. The south end of Islay has a succession of ridges parallel to the sea. The bank by the cycle track below is made of schist and runs down to the side of the bay.

Behind the pods across the back of the bay exposes a much harder rock. It looks a bit like the hornfels we find in the Lakes.

So I was putting together a hypothesis in my head that there had been igneous intrusions that made harder layers but that the schist was in between and wore away. I don't think that can be true because the schist makes up one of the ridges. I'd hoped to find the answer on the Internet but there is little about this end of Islay on a cursory inspection. There is a geological map here https://www.islayinfo.com/islay-geology.html that puts these rocks into the Argyll group https://en.wikipedia.org/wiki/Argyll_Group