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Oklahoma State Soil

Oklahoma State SoilOklahoma’s famous red dirt is on display at Gloss Mountain State Park, in the northwestern part of the state.

Oklahoma is among the states with an official soil. Its soil, adopted in 1987, goes by the unassuming name Port silt loam.

Named after the small community of Port in Washita County, Port silt loam soils are found on flood plains in central and western Oklahoma. They cover a total of about one million acres in 33 of Oklahoma’s 77 counties.

Most of this vast soil domain—part of a mosaic of soils we call the Great Plains—is used as cropland to cultivate alfalfa, wheat, sorghum, and cotton. Some areas are used as pasture or rangeland.

Port soil in Oklahoma ranges from dark brown to dark reddish brown. In fact, visitors are often struck by the redness of Oklahoma’s soils. The redness is caused by iron oxide, the result of the weathering of reddish sandstones, siltstones and shales formed during the Permian Period nearly 300 million years ago.

At the end of the Permian, all the continents were joined together, forming the super-continent Pangaea. If viewed from space, Earth likely would have appeared as a blue and reddish brown marble, the reddish brown identifying the vast deserts of Pangaea’s interior. The greatest continent ever was likely outlined in green, marking the cooler, wetter coastline.

The end of the Permian marked the greatest extinction event, a massive die-off that ushered in a new dynasty: the dinosaurs.

Today, red earth is an ominous reminder of the Dust Bowl, which hit Oklahoma hardest, and climate change. However, it can also identify ancient buffalo wallows.

Some see a symbolic connection between red earth and Native Americans. In fact, Oklahoma City is home to the Red Earth Museum, which puts on an annual Red Earth Festival designed to celebrate Oklahoma’s diverse native cultures.

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