Category:Niobrara Chalk - rock samples

Media in category "Niobrara Chalk - rock samples"

The following 3 files are in this category, out of 3 total.

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  Chalk (Niobrara Formation, Upper Cretaceous; Great Plains, USA) 1.jpg 2,274 × 1,675; 3.18 MB
  
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  Chalk (Niobrara Formation, Upper Cretaceous; Great Plains, USA) 2.jpg 2,323 × 1,686; 3.31 MB
  
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  Chalk (Niobrara Formation, Upper Cretaceous; Great Plains, USA) 3.jpg 2,371 × 2,000; 3.55 MB