Here's why:
* Humid Climate: Alfisols form in regions with moderate to high rainfall and warm temperatures, which are the hallmarks of the eastern US.
* Forest Vegetation: The eastern US is historically covered in deciduous forests, and Alfisols develop under these types of vegetation.
* Mineral Richness: Alfisols are relatively rich in minerals, reflecting the weathering of underlying bedrock in the region.
* Clay Accumulation: A key feature of Alfisols is the accumulation of clay in the subsoil, creating a distinct "B" horizon.
Other important soil types in the humid eastern US:
* Ultisols: Found in the southeastern US, particularly in areas with higher rainfall and warmer temperatures, Ultisols are similar to Alfisols but have higher acidity and lower base saturation.
* Inceptisols: These soils are less developed than Alfisols and Ultisols and are found in areas with shorter periods of soil development or in mountainous regions.
* Mollisols: While not as widespread as Alfisols, Mollisols can be found in the more temperate northern parts of the eastern US, particularly in areas with grasslands.
The specific soil type found in a given location will depend on factors such as the underlying bedrock, topography, and vegetation. However, Alfisols represent the dominant soil order in the humid eastern US, reflecting the region's unique climate and history.
