This study module is related to the Nordland National Park Centre and its close surroundings. The area has many interesting Geological features and cultural monuments from earlier times. The module is aimed at understanding a Geological phenomenon in nature, river terraces, and their formation based upon using a Geo Lab installation. The valley, Saltdalen, has very many river terraces which is easy to see and access.
Fluvial (river) terraces are elongate terraces that flank the sides of floodplains and fluvial valleys all over the world. They consist of a relatively level strip of land, called a “tread,” separated from either an adjacent floodplain, other fluvial terraces or uplands by distinctly steeper strips of land called “risers.” These terraces lie parallel to and above the river channel and its floodplain. Because of the manner in which they form, fluvial terraces are underlain by fluvial sediments of highly variable thickness.
Fluvial terraces are the remnants of earlier floodplains that existed at a time when either a stream or river was flowing at a higher elevation before its channel down cut to create a new floodplain at a lower elevation. Changes in elevation can be due to changes in the base level (elevation of the lowest point in the fluvial system, usually the drainage basin) of the fluvial system, which leads to head ward erosion along the length of either a stream or river, gradually lowering its elevation. For example, down cutting by a river can lead to increased velocity of a tributary, causing that tributary to erode toward its headwaters. Terraces can also be left behind when the volume of the fluvial flow declines due to changes in climate, typical of areas, which were covered by ice during periods of glaciations, and their adjacent drainage basins (Source Wikipedia).