Unit M27

image M27-07


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This is a close-up of the siltstones which occur below the sharp-based sandstone channel of images M27-01 and M27-02. Notice the colour mottling. This is characteristic of soils and paleosols (fossil soils).The dark structures, which are perpendicular to the bedding, probably represent the roots of plants which grew in this soil. They are now shown up by iron oxides occurring in a more reduced form, compared with the surrounding sediments, where the more oxidized iron has typical 'rusty' colours.

  • What does the occurrence of a fossil soil tell us about the environment in which these sediments were formed?
  • How did the environment change from this bed to the overlying sandstone?

Scale: Right-hand scale in cm

Grid reference: 996 324

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