Fluvial processes
Phenomena
Alluvial fan (Svalbard) - fan-shaped deposit of stream. Stream on the foothill lost its gradient and thus the energy to transport material. This material fills the channels and force the stream to divert and form the fan- (or cone-) shaped deposit. Note the U-shaped valley on the other side of the fjord and the Terminoglacial Lake on the left edge of the picture.
Vertical incision (Svalbard) - the proglacial stream originally flowed from the left and formed the wide canyon with flat bottom. After recent breach of terminal moraine on the right side of the picture the stream flows in the new channel. The vertical and headward erosion formed the narrow and deep gorge.
Rapids (USA) - rapids are formed in the places, where headward erosion of the river meets more resistant bedrock. They can also emerge as a result of gradual destruction of the waterfall (tectonic uplift etc.)
Floodplain (USA) - is a semi-flat surface formed by fluvial sediments transported by the river and deposited in the stretches with lower energy. On the opposite bank you can see the fluvial terrace – remnant of the older floodplain, rest of which was eroded.
Canyon (USA) - is a result of vertical erosion (incision) of the river in unconsolidated sediments or rocks with high susceptibility for erosion. The waterfall in the background is formed on the more resistant layer of rocks (in this case by basalts).
Meandering stream (USA) - steep convex outer bank is gradually eroding, and the fine sediments are depositing in the inner gentle concave bank (forming point bar). The deepest place in the river (thalweg) is near the outer bank.
Palaeosoils (USA) - fluvial deposition during major flood events covered well-developed soils with layers of fine anorganic sediments. In some layers the fireplaces of old Native Americans can be found.
Fluvial terraces (USA) - fluvial terraces are remnants of older floodplain surface. This massive complex of more than 6 terraces is formed by gradual uplift of the whole area and vertical and lateral erosion of the river.
Slot canyon (USA) – deep and narrow canyon that is formed by water erosion during frequent flash floods in the semi-arid conditions. They are usually formed in the sandstone or limestone rock.
Gorge (USA) - this narrow and deep canyon - like feature is result of vertical erosion of the river into the tectonically uplifted solid rocks.
Entrenched meander (USA) - this type of meander is formed if the slope of an previously existing meandering stream is suddenly increased (on this example by the tectonic uplift). The resulting vertical cutting will form this incised meander.
Pothole (Kinder Scout, Peak District, UK) - These small holes were formed by erosional activity of turbulent flow in a stream.
Mudcracks (Morocco, Quarzazate) - Mudcursl in abandoned river channel.
Mudcracks (Morocco, Erfoud) - Mudcracks in abandoned dried pond.
Mudcracks (Morocco, Quarzazate) - Mudcracks in abandoned dried pond.
Raindrop impressions (Morocco, Quarzazate) - Raindrop impressions on surface of mudcrack in abandoned river channel.
Mudcracks (Morocco, Erfoud) - Mudcracks in abandoned river channel.
Mudcracks (Morocco, Quarzazate) - Orthogonal mudcracks with interconnected cracks in abandoned dried pond.
Mudcracks (Morocco, Erfoud) - Size of mudcracks depends on thickness of the clay bed.
Mudcracks (Argentina. Parque Nacional Sierra de las Quijadas) - Fossil mudcracks from Triassic rocks.
Mudcracks (USA, California) - Curved mudcracks in abandoned dried pond.
Mudcracks (Argentina, Park Nacional Talampaya) - Small mudcracks on slope of clay mound.
Mudcracks (Morocco, Erfoud) - Mudcracks of different size.
Patterned ground (Morocco, Merzouga) - Polygons of dessicated clay ground patterned with small rocks.
Patterned ground (Morocco, Merzouga) - Polygons of dessicated clay ground patterned with small rocks.
Lamination (Argentina, Parque Nacional Sierra de las Quijadas) - Lamination on Triassic siltstones.
Lamination (Argentina, Parque Nacional Sierra de las Quijadas) - Lamination on Triassic siltstones.
Lamination (Argentina, Parque Nacional Sierra de las Quijadas) - Lamination on Triassic siltstones.
Lamination (Morocco, Quarzazate) - Lamination on recent sand in abandoned rivel channel.
Lamination (Argentina, Parque Nacional Sierra de las Quijadas) - Pitted surface of the lamina from Triassic siltstones.
Evaporites (California, Death Valley) - Salt and clay form large polygonal ground.
Evaporites (California, Death Valley) - Weathering processes scupt surface of the salt pan into „Devils Golf Course“.
Mudcracks (Argentina, National park Ischigualasto) - Mudcracks of different size.
Ripple marks (Morocco, Erfoud) - Sinuous-crested ripple marks in in abandoned river channel. This type originate by an unidirectional flow.
Ripple marks (Morocco, Erfoud) - Sinuous-crested and isolated (linguoid) ripple marks in in abandoned river channel. This type of ripple marks has cross-bedding in a cut that is perpendicular to flow.
Evaporites (California, Death Valley, Badwater Basin) - Salt pool with salt flats.
Evaporites (California, Death Valley, Badwater Basin) - Salt crusts crystallized from salt pool.
Evaporites (Argentina, San Rafael, Embalse del Nihuil) - Salt crystals on surface of a salt flat.
Evaporites (Argentina, San Rafael, Embalse del Nihuil) - Salt crystals on salt crust.
Evaporites (Argentina, San Rafael, Embalse del Nihuil) - Clusters of salt crystals on a surface of thin salt crust.