Fluvial terraces are elongated 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. River 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 downcut 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 headward erosion along the length of either a stream or river, gradually lowering its elevation. For example, downcutting 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 glaciation , and their adjacent drainage basins.
18-588: (Redirected from Rangitīkei ) Rangitikei may refer to the following in New Zealand: Rangitīkei River , one of country's longest rivers Rangitikei District , a district council in the Manawatu-Wanganui Region Rangitīkei (New Zealand electorate) , a current general electorate 1978 Rangitikei by-election , a by-election held in 1978 Wanganui and Rangitikei ,
36-541: A ferry linked Tangimoana to Scotts Ferry. Onepuhi, or Onepuehu, bridge was shown on the 1941 map, but missing from the 1968 and later maps. Further decking for the 807 ft (246 m) long Onepuhi bridge was suggested in 1958. The river is a popular leisure and recreation area for jetboating, white water rafting, kayaking and fishing, and includes public camp grounds along its banks, including Vinegar Hill, New Zealand . Its sheer vertical "paapa" (clay) cliffs (unique to this part of New Zealand) and deep canyons provide
54-510: A historic general electorate Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title Rangitikei . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Rangitikei&oldid=1230548941 " Categories : Disambiguation pages Place name disambiguation pages Hidden categories: Short description
72-424: A possible thin layer of alluvium) is left above either a stream or river channel. These bedrock terraces are the strath terraces and are erosional in nature. Paired and unpaired terraces : Terraces of the same elevation on opposite sides of either a stream or river are called paired terraces . They occur when it downcuts evenly on both sides and terraces on one side of the river correspond in height with those on
90-543: Is different from Wikidata All article disambiguation pages All disambiguation pages Rangit%C4%ABkei River The Rangitīkei River is one of New Zealand 's longest rivers, 253 kilometres (157 mi) long. Its headwaters are to the southeast of Lake Taupō in the Kaimanawa Ranges . It flows from the Central Plateau south past Taihape , Mangaweka, Hunterville , Marton , and Bulls , to
108-429: Is reached and it can transport the material rather than deposit it. This equilibrium may last for a very short period, such as, after glaciation, or for a very long time if the conditions do not change. The fill terrace is created when the conditions change again and either a stream or river starts to incise into the material that it deposited in the valley. Once this occurs benches composed completely of alluvium form on
126-544: The South Taranaki Bight at Tangimoana , 40 kilometres (25 mi) southeast of Whanganui . The river gives its name to the surrounding Rangitikei District . In 1897 the river flooded and all the bridges over it ( Vinegar Hill , Onepuhi, Kakariki railway bridge and Bulls) were damaged or destroyed. Port of Rangitikei, at the mouth of the river was also washed away and never rebuilt. Other notable floods were in 1882, 1917, 1936, 1958, 1965 and 2004. Until 1908
144-520: The Rings: The Fellowship of the Ring . Both rainbow and brown trout throughout the river system with fish in the upper reaches reaching trophy size (i.e. over 4.5 kg) with the average through the rest of the system being around 1.5 to 2 kg. Fish numbers are good throughout the system though there are fewer fish per kilometre in the upper reaches. This is made up for by the quality and size of
162-477: The fill terraces mentioned above, but they are erosional in origin. Once the alluvium deposited in the valley has begun to erode and fill terraces form along the valley walls, cut terraces may also form below the fill terraces. As either a stream or river continues to incise into the material, multiple levels of terraces may form. The uppermost being the fill terraces and the remaining lower terraces are cut terraces. Nested fill terraces: Nested fill terraces are
180-638: The fish being larger in this section. The Springvale Suspension Bridge crosses the Rangitīkei River on the Taihape–Napier Road (known as the Gentle Annie). It is located on the Ngamatea Plateau in the district of Ngamahanga , 41 km north–east of Taihape and 111 km west of Napier . It was built to support farming which increased in the inland Patea region after World War I and
198-506: The need to transport stock and wool to the port at Napier . The bridge was designed by Rangitīkei County engineer Sydney Mair and built by William Salt. Construction commenced in 1923, the bridge opened in 1925 and it was known as the Rangitīkei Bridge or Erewhon Bridge after the name of the farming block. The name Springvale came from the nearby sheep farm. The bridge was replaced by the nearby Callender–Hamilton bridge in 1970 as it
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#1732855704884216-430: The other side. Paired terraces are caused by river rejuvenation . Unpaired terraces occur when either a stream or river encounters material on one side that resists erosion, leaving a single terrace with no corresponding terrace on the resistant side. Fluvial terraces can be used to measure the rate at which either a stream or river is downcutting its valley. Using various dating methods, an age can be determined for
234-538: The perfect setting for adventure activities such as bungy jumps and flying fox rides. The cliffs, which display oxygen isotope stages , have been incised into the soft Quaternary , 2.6 to 1.7 million year old, marine sediments as the land has risen since the last ice age. The rise has left 19 terraces , which have been mapped. Part of the river was used as the Anduin River in Peter Jackson 's movie The Lord of
252-496: The relative elevations of the surface of these terraces. Fill terraces: Fill terraces are the result of an existing valley being filled with alluvium . The valley may fill with alluvium for many different reasons including: an influx in bed load due to glaciation or change in stream power which causes the valley, that was down cut by either a stream or river, to be filled in with material (Easterbrook). The stream or river will continue to deposit material until an equilibrium
270-420: The result of either a stream or river downcutting through bedrock. As the flow continues to downcut, a period of valley widening may occur and expand the valley width. This may occur due to an equilibrium reached in the fluvial system resulting from: slowed or paused uplift, climate change, or a change in the bedrock type. Once downcutting continues the flattened valley bottom composed of bedrock (overlain with
288-490: The result of the valley filling with alluvium, the alluvium being incised, and the valley filling again with material but to a lower level than before. The terrace that results for the second filling is a nested terrace because it has been “nested” into the original alluvium and created a terrace. These terraces are depositional in origin and may be able to be identified by a sudden change in alluvium characteristics such as finer material. Strath terraces: Strath terraces are
306-463: The sides of the valley. The upper most benches are the fill terraces. As it continues to cut down through the alluvium the fill terraces are left above the river channel (sometimes 100 m or more). The fill terrace is only the very highest terrace resulting from the depositional episode; if there are multiple terraces below the fill terrace, these are called "cut terraces". Cut terraces: Cut terraces, also called "cut-in-fill" terraces, are similar to
324-711: Was no longer able to carry heavy trucks. As an early example of a suspension bridge with reinforced concrete towers its importance in engineering heritage was recognised by Heritage New Zealand designating it as a Category II historic site. The bridge has a span of 61m supported by 7m high concrete towers at either end. The deck is made of wood and at 2.4m wide is a single lane. Fluvial terrace There are two basic types of fluvial terraces, fill terraces and strath terraces. Fill terraces sometimes are further subdivided into nested fill terraces and cut terraces. Both fill and strath terraces are, at times, described as being either paired or unpaired terraces based upon
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