Clay-ironstone concretion in blocky claystone subunit, Lake Neosho Shale

A clay-ironstone concretion in blocky claystone lies near the center of
this photograph. It is surrounded by a rim of yellowish orange iron oxide
stains in the claystone. The change in matrix color from brownish gray
to dark gray a few centimeters below the pocketknife marks the contact
between the calcareous shale subunit of the Lake Neosho (below) and
the blocky claystone subunit (above).

View close-up

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