Soil Color Ideas

Premise

Soil color generally varies in a predictable pattern with depth according to surface vegetation, clay mineralogy and parent material. Highly contrasting parent geology influences soil color within Pinnacles via four main processes:

1. Original color of parent material
   sedimentary sources: grey, yellow, white
   granitic sources: yellow to orange
   volcanic sources: pink, orange, white, green
2. Landscape age
   older landscapes generally have redder hues (Fe-expression) from longer chemical weathering
3. Particle size distribution of parent material and the resulting field capacity of a soil formed from it
   coarse textures result in lower field capacities, limiting vegetation growth and subsequent accumulation of organic matter in the surface horizons
4. Weathering rate of parent material
   sedimentary materials derived from granitic sources (grey to yellow hues) have high levels of quartz and are therefore less susceptible to chemical weathering than volcanic rocks (redder hues)

Soil colors from Pinnacles: Moist colors in the L*U*V* color space (629 horizons).

Query Samples

All Horizons along with horizon thickness

Horizon Thickness-weighted Average for Subsurface Horizons

Pedon Color (spatially) Averaged within 500 meter grid, from profile thickness-weighted average

Visualization in R

Setup R environment

Pinnacles Soil Color Map 1

Plot colors from all horizons, for all pedons. Note that a small amount of noise is added to the (x,y) coordinates of each pedon, so that the colors from each horizon do not overlap. Thinner horizons are depicted with a more transparent color.

Pinnacles Soil Color Map 2

 
Plot colors from all horizons, for all pedons. Note that a small amount of noise is added to the (x,y) coordinates of each pedon, so that the colors from each horizon do not overlap. Thinner horizons are depicted with a more transparent color.

 
Colors of Pinnacles

Can soil color be used to infer parent material source?
Approximate identification of parent material source based on soil colors. Note that this is a very coarse estimation, especially since large regions of the sedimentary materials were originally derived from granitic sources. The general trend visible in the clustering does match a rough approximation of the park geology.

Pinnacles Soil Color Clustering Idea 1: PAM clustering of mean subsoil color (horizon thickness-weighted) for 170 pedons.