GeoGirls use ground-penetrating radar
Detailed Description
GeoGirls use ground-penetrating radar to locate rock and ash layers from past eruptions at Mount St. Helens (Mount Adams is pictured in the background).
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock () or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
