The following is largely copied from "Handbook for soil thin section description" (Bullock P., N. Fedoroff, A. Jongerius, G. Stoops and T. Tursina, 1985) and "Soil microscopy and micromorphology" (FitzPatrick, 1993)

Micromorphology is the branch of soil science that is oncerned with the description, interpretation and, to an increasing extent, the measurement of components, features and fabrics in soils at a microscopic level, i.e. beyond that which can readily be seen with the naked eye. It is fundamental to an understanding of the processes involved in soil formation whether they can be produced by the normal forces of nature or artificially induced by the effect of man. The main principle of soil micromorphology that separates it from most other pedological techniques is that the soil is examined in an undisturbed condition. The building elements are considered from the stand point of view of the way they fit together, not only as mere constituents or compounds.

Micromorphology is largely a collection of concepts supported by tools and techniques that are used to acquire specific information abouth the soil that cannot be obtained directly with other analytical methods. It was never intended to be a discipline unto itself, but rather to be used with other tools to gain insight into how soils form and function.

Sampling is a critical part of all micromorphological studies. Any mistakes made in sampling will affect what is seen in the thin section and may cause incorrect interpretations and conclusions to be made about the soil material being studied. It is essential that all samples collected represent the soil material as it exists in the field. Collecting such representative samples is difficult because soils are very heterogeneous and even the largest thin sections contain only a very small volume of soil.

Serveral considerations must be taken in order to collect representative soil samples:

1. the purpose of the investigation. Sampling techniques must meet the objectives of the study. The purpose of the study will dictate how samples will be collected, how many, and the volume of soil to be sampled.
2. Site selection and supplemental data. The thin section sample must be representative of the soil at the site that is being studied.
3. Sizes of samples and thin sections. The size needed depends on the size of the features of interest and their distribution.
4. The timing of sampling. Due to the dynamic nature of many soils, marked differences may occur depending onmoisture content. Also, onplowed soils, there is a marked difference in microstructure depending on the time after plowing.
5. The number of samples to be taked. Due to soil heterogeneity, a number of samples may have to be taken to fully characterize the soil unit. Sampling strategies depend onnatural soil heterogeneity, the feature of interest, and statistical accuracy desired.
6. The method of securing samples. There are a number of techniques used to obtain samples. Caution should be exercised to ensure that artifacts are not introduced by the sampling or treatments used before impregnation.
7. Sample orientation. The orientation of the thin section sample can be critical to some investigations, and in all cases it must be known. If feature orientation is not known, both horizontal and vertical sections should be obtained.
8. Documentation, transport, and storage of samples. All samples should be properly labeled and bagged. Profile descriptions should be complete and profile sketches made to show sampling locations with respect to pedological features or horizons.

This page (http://www.ces.ncsu.edu/plymouth/programs/thin.html) created by
Vera MacConnell, Research Technician, I on December 1, 1997.
Last Updated on December 8, 1997.