10 or more. These soils have deeply weathered mottled horizons. Characteristic of this type of paleosol is a stable microstructure of sand-sized spherical micropeds of iron-stained lay. Very old, often amounting to tens of millions of years. Found on stable continental locations on gentle slopes of plateaus, terraces, and plains. The natural vegetation for Oxisols is a rainforest. Vertisol (swelling clay soil) Horizons: A, Bw, & C These are uniform, thick, clayey soils that have deep, wide cracks. Cracking can produce a hummock-and-swale topography. Mostly composed of smectitic clays. Most Vertisols are found on intermediate to basaltic materials. Found mainly in flat terrain at the foot of gentle slopes. Climate and vegetation are dry and sparse enough that alkaline reactions can be maintained. Vegetation ranges from grassland to open woodland, with wooded grassland being common. Mollisol (grassland soil) Horizons: A, sometimes Bt, Bk, sometimes By, & C Well-developed, base-rich, surface horizon of intimately mixed clay and organic matter. An abundance of fine root traces and crumb ped structures are characteristic of this paleosol. The surface horizon characteristic of this paleosol is created by fine root systems of grassy vegetation and the burrowing activity of many soil invertebrate species. Mollisols are found in low, rolling, or flat country. Aridisol (desert soil) Horizons: A, sometimes Bt, Bk, sometimes By, & C Forms in arid to semi-arid regions, and that lack of rain allows for the creation of shallow calcareous, gypsiferous, or salty horizons. These cements form large nodules or continuous layers. Light-colored, soft, and often vesicular surface horizon. Subsurface horizons are not cemented with any of the aforementioned cements. Mostly found in low-lying areas because steep slopes in arid regions tend to be eroded back to bedrock. Vegetation is sparse and includes prickly shrubs and cacti. Gelisol (permafrost soil) Horizons: A, sometimes By, & C Soils with ground ice or other permafrost features within one meter of the surface. In paleosols, locations of ice can be preserved as clastic dikes, freeze banding, or other deformations created by ground ice. Tillites and other glacigenic deposits are indicative of Gelisols. These soils form under polar desert, tundra, and taiga vegetation. Includes a surprising array of histic epipedons, desert pavements, salic, and calcic horizons. Many other factors, such as ped structures, such as the presence of blocky, angular or granular peds and fabric type, like clinobimasepic plasmic fabric, are structures that can help one identify