Map 90

Click here for a full-size version of this week’s map.

This map is a proportional symbol map of the world. (Do you need a refresher on what a proportional symbol map is? Visit our “Basics” page for a quick primer.) This map was made for us by David P., one of our regular submitters, whom you might remember as the co-winner of our second five-week challenge. Thanks very much to David for coming up with the concept for this map and putting it together. As always, your job is to figure out what this proportional symbol map represents.

Stumped? Check back Tuesday, Wednesday, Thursday, and Friday for hints about where to focus your investigation. The answer will be posted on Monday, May 21, 2018. Good luck!

Tuesday’s hint: Many of the dots on this map are fairly recent additions. Canada, in particular, would not have had any dots until the 1990s.

Wednesday’s hint: Intriguingly, one of the dots is actually in the Atlantic Ocean, just off the coast of Namibia. It’s the only dot that is not on land.

Thursday’s hint: Another thing that many of the areas with lots of dots on this map have in common is that they are home to some of the oldest rocks anywhere on the earth’s surface.

Friday’s hint: Some of the dots on this map are close to the city of Kimberley, South Africa. Kimberley gave its name to a type of igneous rock called “kimberlite,” which is found in all the places that have dots on this map.

Answer: Click here to see an explanation of the answer to this week’s map question.

Next map: Click here to try out our newest map question.