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.
Closeup of a freeze core collected from Elk Lake, MN in 2024. The photo shows light and dark layers reflecting the different types of sediment that settle to the bottom of the lake in each season.
Public Domain.
