It is a turning point of lay. It means insert, mix, alternate. Place one thing followed another alternately. As a verb, lay it is engaging, lock, enter into a discussion.
Shoals is when something is this mixing with something else and is no longer one or another but has qualities of both of them, as when they begin to ripen the fruit and show several mixed colors, or cereals and show mixed with the golden green.
SHOALS: INTERMINGLING, CONFUSING. INTRODUCE SOMETHING INTO SOMETHING ELSE.