When Speedy was first learning how to make layered cocktail drinks, he followed recipes which conveniently specified which ought to be poured first so that the proper layers are formed.
The drink above, for instance, consists of grenadine and creme de menthe while the next one appears to be Kahlua, creme de menthe and Bailey’s. I have forgotten now what they are called — that is, if Speedy ever told me — and they should have been posted over the Christmas holidays because of their festive colors. But, never mind, there will be a lot of other layered drinks in the future and I will not forget to post them again. But that’s not really the point.
The point is that I found a chart (which also appears in another website as a bulleted list — who copied who, I don’t know) listing the specific gravity of drinks and mixers. Using the chart as a guide, we can now freely experiment with combinations instead of merely following someone else’s formula. Peach liqueur over Cherry liqueur sounds like a good combination.