Cliffs

Cliffs are steep rock faces that rise abruptly from their surroundings, typically vertical or near-vertical, with little to no soil cover. They occur in coastal regions where waves erode at the base of a landform, along river valleys, and where tectonic uplift or faulting creates vertical faces in mountainous terrain. Common cliff environments include coastlines, fjords, and escarpments.

Cliffs form primarily through erosion and weathering processes. In coastal settings, wave action undercuts the base of a rock, creating an overhang that eventually collapses, leaving a retreating cliff edge. Weathering, including freeze-thaw cycles, salt crystallization, and chemical weathering, weakens exposed rock. Rock type and structure control the shape and rate of retreat; beds, joints, and faults create steps and ledges that influence erosion pathways.

There are several common cliff types. Sedimentary cliffs such as chalk, limestone, sandstone, and shale often reveal layered strata. Igneous and metamorphic cliffs, including granite, basalt, and slate, tend to be more resistant though exposed joints can produce steep faces. Inland cliffs can form in river valleys or along fault lines, while coastal cliffs typically expose marine sedimentary sequences.

Ecology and hazards: cliff faces host specialized plant communities and provide nesting sites for birds. They also pose hazards to climbers, hikers, and property, with sudden collapses or rockfalls possible after heavy rainfall or freeze-thaw cycles.

Notable examples include the Cliffs of Dover in England, the Cliffs of Moher in Ireland, and the White Cliffs of Dover along parts of the English Channel coastline.