PEAT. I posted here on an article by Seth Porges which argued that it was happy accident that scotch whiskey arose in poor and remote places.
I had posted here that my father used to say at the dinner table that our Irish and Danish ancestors had in common that rather than fight for their land, they had moved to parts of the world where nobody else would want to settle. The boggy land made it unattractive for more warlike people.
Andrew Jefford elaborates on some reasons why bogs are unattractive places to live: “These are the plants of an irredeemably wet place, a place from which the water cannot drain.” Much of the mass is made up of sphagnum moss (“bog moss”). (Other plants in a peat bog include bog cotton and bog myrtle). Sphagnum moss can absorb eight times its own weight in water. Peat has to be stacked and dried over a summer, and it may then lose 75% of its water content (but not all of it). Banks of peat up to ten yards deep are found on Islay.
The moisture makes peat a problematic fuel. The plants in the top layer of a peat bog are still alive, and the top layer is preferred for home fires on Islay. More warmth and less smoke. The bottom layer where the plants are dead is preferred for distilleries because it burns with a lot more smoke, providing more flavor.