Earth: Inside and Out
Rock Dating Gallery

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Topic of Focus: What is the Age of the Earth?
"...we can determine very precisely and with great accuracy the ages of many geologic materials."
-- Ed Mathez
Illustrations from the Hall of Planet Earth
Click on an image for a closer look.
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Dating Rocks with Radioactivity
Telling Time Precisely
Stillwater Gabbro
Introduction to Stillwater Gabbro
stillwater_th.gif Stillwater Gabbro
Stillwater gabbro, in the Hall of Planet Earth at the AMNH...
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stillwater_closeup_th.jpg Gabbro Close-up
Close-up photo of the Stillwater gabbro...
Stillwater Gabbro: Collecting and Dating
Computing the Rate of Decay
stillwater_field_th.jpg Fieldwork in Montana
Museum scientists Ed Mathez and Margaret Carruthers with colleagues...
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stillwater_collect_th.jpg Collecting a Sample for the Hall
Elf French and Ed Mathez collect a boulder from the Stillwater Complex...
stillwater_vials_th.jpg Vials of Crushed Rock
In order to date the gabbro, it was crushed up...
stillwater_vials_th.jpg Rate of Decay Graph
Initially, the three minerals (P, C, O)...