On a world map, Costa Rica is the country directly north of Panama and south of Nicaragua. It is located in Central America and has an extensive Pacific and Caribbean coast.

Already this year, seven million acres have burned in North America. These fires also generate massive plumes of smoke, which carry tiny dangerous particles.

Over decades, geologists had built up a history of eastern North America by mapping rocks on Earth’s surface. But they got a much better look, and many fresh insights, starting around 2010.

As we get ready to celebrate our nation’s birthday with the signing of the Declaration of Independence in Philadelphia in 1776, let’s look at what was happening on the other side of North America.