The Great Unconformity: What a Missing Billion Years Can Tell Us About Earth — An accessible, evidence-led geology feature for readers interested in Earth science and geological history.
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An unconformity is a surface that represents a gap in the geological record. It can form when deposition stops, older rocks are eroded, or both processes o
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Faults are fractures along which rocks have moved relative to one another. They record deformation, influence groundwater pathways and help explain the dis
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Folds are bends in rock layers produced when rocks deform under stress. They are common in mountain belts and sedimentary basins, where compression, burial
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A caldera is a broad volcanic depression formed when the ground collapses or subsides after a large volume of magma is withdrawn from a shallow reservoir.
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A river delta forms where a river enters a standing body of water and deposits sediment faster than waves, tides and currents can remove it. Deltas ar
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Alluvial fans are fan-shaped sediment deposits that form where streams emerge from confined valleys onto flatter terrain. They are common in arid and
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Karst landscapes develop where soluble rocks, especially limestone, are dissolved by water. Sinkholes, disappearing streams, springs and caves are sur
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Columnar basalt is a striking volcanic rock formation in which cooling lava is divided into long, polygonal columns. The geometry is natural: it devel
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