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. National Park Service Search Exiting nps.gov Rate the Lesson Plan Student Activities Earth Blocks Grade Level: High School: Ninth Grade through Twelfth Grade Subject: Science Geologists generally accept that events of the future will resemble those of the past. For this reason, they investigate the origin of rocky layer