NY, I just noticed your new tag line. If it's not new, then I am unobservant.
"Thickly settled" was one of the list of expressions that I had to make a list of and have explained to me by my cousin, when I moved back to MA. They all were things you had to know to pass the written dirver's test here. While thickly settled was one I kind of got, things like frost heave and reverse curve vexed me. I was just thinking about this yesterday, so when I saw your post, I laughed.