But this 41-km-wide crater sits amid a halo of spectrally immature soils
, ones that have not yet been space-weathered sufficiently to darken.
Inceptisols are immature soils
of humid and subhumid regions that have altered horizons with evidence of chemical and physical change, but still have some weatherable material and lack a clear illuviated zone (Figure 3-12).
These relatively immature soils
often retain some characteristics of the unmodified rock, such as its color or particle size.
Some original characteristics of the microflora of these soils have been pointed out, especially the abundance of actinomycetes, the lack of certain fungal groups, and the great influence of plants and organic matter on the evolution of these immature soils
. The importance of organic matter in ultramafic soils has to be taken into account in revegetation after mining.