I was thinking of the Highland Granite tartan and also of the rock a few yards under my feet. I began to wonder . . .

I know much of the Scottish highlands are very rough and rocky. So, is much of the rock, geologically, granite or is it of another type?

In my (regional) area, we have A LOT of granite. A very large lump lies just below most of Atlanta, North Georgia, Upstate South Carolina, Alabama, Tennessee, and more. The largest exposed lump is Stone Mountain near Atlanta, but that lump extends WAY out in all directions.

So, is Grantite a commonality of these two regions so many thousands of miles seperated?