Dictionary of Geotourism

2020 Edition
| Editors: Anze Chen, Young Ng, Erkuang Zhang, Mingzhong Tian

Concretion; Nodule

Reference work entry
DOI: https://doi.org/10.1007/978-981-13-2538-0_385
A concretion is a type of nodule in sedimentary rocks with a composition different from that of the surrounding rocks. Nodules have different sizes and shapes. They are usually spheroidal, ovoid or irregular, and they can range in size from a few centimetres to several metres. Nodules can be distributed intermittently along a layer or spread through different layers. Common nodules include calcareous nodules, ferrous nodules and siliceous nodules (Fig. 44).
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© Springer Nature Singapore Pte Ltd. 2020