River incision in the context of "Tectonic uplift"

An alluvial plain is a plain (an essentially flat landform) created by the deposition of sediment over a long period by one or more rivers coming from highland regions, from which alluvial soil forms. A floodplain is part of the process, being the smaller area over which the rivers flood at a particular time. In contrast, the alluvial plain is the larger area representing the region over which the floodplains have shifted over geological time.

As the highlands erode due to weathering and water flow, the sediment from the hills is transported to the lower plain. Various creeks will carry the water further to a river, lake, bay, or ocean. As the sediments are deposited during flood conditions in the floodplain of a creek, the elevation of the floodplain will be raised. As this reduces the channel floodwater capacity, the creek will, over time, seek new, lower paths, forming a meander (a curved path). The leftover higher locations, typically natural levees at the margins of the flood channel, will be eroded by lateral stream erosion, local rainfall, and possibly wind transport if the climate is arid and does not support soil-holding grasses. These processes, over geologic time, will form the plain, a region with little relief (local changes in elevation) yet with a constant but slight slope.

Tower karst are tall rock structures made up of soluble rock such as limestone. Tower karst forms as near-vertical joints and fractures are eroded downward by solution, leaving parts of a previously coherent rock mass isolated from each other. Tower karst is most common in tropical regions, although it may form in other climates as well.

Examples include Khao Phing Kan, also known as James Bond Island, in Thailand, and Cat Ba Island in Vietnam.

Río Negro (Spanish pronunciation: [ˈri.o ˈneɣɾo]; Black River) is the main river of Patagonia in terms of the size of its drainage basin, its associated agricultural produce and population living at its shores. In eastern Patagonia it is also the largest by flow rate. The river flows through the Argentine province of Río Negro which is named after it. Its name comes from the literal translation of the Mapuche term Curu Leuvu, although the water is more green than black. Formerly, it was also known as "river of the willows" because of the big number of weeping willows that grow along the bank. It is 635 km in length.

It originates from the junction of the Limay River and Neuquén River at the border with the Neuquén Province, and flows southeast incised through steppes to the Atlantic Ocean at 41°01′20″S 62°47′25″W / 41.0223°S 62.7903°W / -41.0223; -62.7903, near El Cóndor beach resort some 30 km (19 mi) downstream from Viedma, Río Negro province's capital.