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The largest deposit of loess in the United States which is the Loess Hills along the border of Iowa and Nebraska, has survived intensive farming and poor farming practices. For almost 150 years, this loess deposit was farmed with mouldboard ploughs and tilled in the fall, both intensely erosive practices. At times it suffered erosion rates of ...
Local regression or local polynomial regression, [1] also known as moving regression, [2] is a generalization of the moving average and polynomial regression. [3] Its most common methods, initially developed for scatterplot smoothing, are LOESS (locally estimated scatterplot smoothing) and LOWESS (locally weighted scatterplot smoothing), both pronounced / ˈ l oʊ ɛ s / LOH-ess.
Typical loess is loess that is deposited during late Pleistocene and Holocene. It is formed under arid or semi-arid conditions. [4] Secondary loess is loess that is compacted by upper loess and does not experience the weathering and carbonation process. Also, it is formed by the transformation of fluvial and lake loess in semi-arid areas. [4]
Loess is known locally as "sugar clay" because it can be extremely hard when dry, but when wet, loses all cohesion. The Loess Hills of Iowa are remarkable for the depth of the drift layer, often more than 90 feet (27 m) deep. The only comparable deposits of loess to such an extent are located in Shaanxi, China. [1]
Loess deposits are found further from the original source of sediments than ergs. An example of this is the Sand Hills of Nebraska, US. Here vegetation-stabilized sand dunes are found to the west and loess deposits to the east, further from the original sediment source in the Ogallala Formation at the feet of the Rocky Mountains. [6]
Floodplain deposits consist of up to six distinct Touchet Beds, as well as loess silt and fine sand. These alluvial and loess deposits narrow as they approach the basalt valley walls, and thicken into the central valley, with a maximum sediment thickness of between 20 and 100 ft (6 and 30 m). Due to the elevation of the valley, only six of the ...
Loess deposits tend to be thinner than those found in 47e to the west, generally less than 25 feet in depth except along the Missouri River where deposits are thicker. Potential natural vegetation is a mosaic of mostly tallgrass prairie and areas of oak-hickory forest.
The high fertility soils of the Loess Belt attracted many people to pursue plantation agriculture in the 1800s. Hardwood trees dominate in loess deposits north of Vicksburg, particularly sweet gum, basswood, water oak, cherrybark, poplar and bitternut. A few small prairies developed atop Cretaceous and Eocene chalk.