| 1. | This type of soil is granular with tuffaceaous material and concretions.
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| 2. | There is an important distinction to draw between concretions and nodules.
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| 3. | This process results in roughly spherical concretions that grow with time.
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| 4. | It also occurs in low-temperature clay-ironstone concretions.
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| 5. | Thus, technically speaking, they are concretions instead of nodules.
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| 6. | The concretions grew larger as the circulating waters deposited more layers.
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| 7. | All ontogenetic stages of the beetle are present in the concretions.
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| 8. | Nodular lumps of pyrite and crystals of septarian concretions are also common.
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| 9. | Some of the concretions are grooved spheres with ridges around their circumference.
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| 10. | Here opal is found as a kernel in small concretions.
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