Today’s puzzle uses a style of mechanism I’ve never tried before. The level of difficulty is a notch above most of the MMMs I’ve posted lately.
The puzzle steps into the Hit Parade spotlight to ask the musical question
What might replace the isolated black squares to get an iconic #1 song from the 1950s?
Nudges will appear Wednesday.
Thanks to @Abide and @Al Sisti for test-solving and advice, and to @Joe Ross, without whom none of what you see below on this post would be there.
Geological Rings crosshare
Geological Rings PUZ
Geological Rings PDF
Geological Rings spreadsheet
![Image](https://www.xword-muggles.com/puzzles2/20230724-MMM-Geological%20Rings.png)