RT @USGS: Celebrate #NationalParkWeek with this historic USGS publication from 1882: [PUB] Tertiary history of the Grand Cañon District, wi…
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Celebrate #NationalParkWeek with this historic USGS publication from 1882: [PUB] Tertiary history of the Grand Cañon District, with atlas: https://t.co/3Nw6WKHjvj https://t.co/dx7uvvGm37
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RT @USGS: Celebrate #NationalParkWeek with this historic USGS publication from 1882: [PUB] Tertiary history of the Grand Cañon District, wi…
127 followers
RT @USGS: Celebrate #NationalParkWeek with this historic USGS publication from 1882: [PUB] Tertiary history of the Grand Cañon District, wi…