Note:  Images in this section were copied without permission from the Soil Classification System Soil Taxonomy slide set published by the Western Regional Soil Survey Work Group, Western States Agricultural Experiment Stations dated November 1976. Do not copy these images! Most of the accompanying descriptions were taken directly from the descriptive pamphlet that accompanied the slide set.  One image (the last) is from the Marbut Memorial slide collection prepared and distributed by the American Society of Agronomy, Madison, Wisconsin.

 

Mollic epipedon

The mollic epipedon is composed of the A horizon and the upper, darker part of the Bt horizon. The A extends to 12-14" (scale is in feet). Note the sudden onset of blocky structure immediately below the mollic epipedon. This is the Crete silt loam in Nebraska. The soil is classified as a Pachic Argiustoll. The soil forms in calcareous silt loam Peoria loess under grass on undulating and gently rolling surfaces.

 

Argillic Horizon

The argillic horizon starts about 10 " deep and continues downward at least to the bottom of the pit. Note the strong prismatic structure. Clayskins are prominant. This is the Renfrow silt loam, a Udertic Paleustoll.

Natric Horizon

The natric horizon is at about the 11-16" depth. It is characterized by prismatic and columnar structure. Note the mollic epipedon, thin albic horizon, the Bt (natric) horizon, and stratified sediments with salt efflorescence in the substratum. This soil represents the Post silt loam, a Typic Natriustoll (located in Montana).

The rounded white columnar tops are characteristic of natric horizons. This is the Arvada series found in Montana

This soil also shows strong columnar structure associated with the natric horizon