Earth detectives

Lake Superior Agates

Geology is the study of the history of the earth, which includes its rocks and fossils.

Geologists study this history to find out how the earth looked in the past and how it has changed. Geologists are earth detectives. They piece together small bits of information to create the story of the earth. Geologists try to understand how rocks were created and destroyed. The events which shaped the earth are put in order, from oldest to youngest, to understand how the earth changed over time.

Geologists break time down into geologic time units called eras. Each era contains smaller time units called periods. Check out our Minnesota geologic time table. Its columns show the different eras and periods of time; what kind of rocks were formed in Minnesota; what geologic events were happening in Minnesota; and what kind of animal life existed during each era and period. Look down the columns "Rocks in Minnesota" and "Events in Minnesota." Why is there no information during some periods? The answer: no rocks from these time periods have been found in Minnesota! The rocks were either destroyed, eroded away, or never formed. Without the rocks, it is harder for geologists to tell what was going on in Minnesota during these periods.

Try answering the following questions using the geologic time table:

Q. In which era do you find the Jurassic period?
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Q. What kind of rocks were formed in Minnesota during this time?
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When you think of the Department of Natural Resources,
you probably think of fishing, hunting and state parks. But did you know the DNR also has a Division of Lands and Minerals? The Division of Lands and Minerals is responsible for managing 12 million acres of state-owned mineral rights. A wide variety of expertise is needed to manage the state's mineral resources.

The Division of Lands and Minerals staff includes geologists, biologists, hydrologists, foresters, geographers, lawyers, computer experts, office assistants, accountants, technicians, mining engineers, and chemists. The staff works to ensure that all stages of mining are done in an environmentally safe way and that money is generated for the state and its citizens.

What does the Division of Lands and Minerals do?

  • lease (rent) mineral rights to exploration companies
  • find out who owns mineral rights
  • visit exploration and mining sites to make sure laws are being obeyed (including environmental laws)
  • collect mineral samples from around the state
  • operate one of the nation's largest drill core libraries
  • research new methods for environmental protection and new mining technology
  • provide information on minerals and mining.