Field Analysis:How Pores

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SASSA Home Page ⇒ Field Analysis Home Page ⇒ Field Recording ⇒ How? ⇒ Porosity

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Contents 1 Soil porosity and roots 1.1 Soil pore type 1.2 Pore frequency 1.3 Pore orientation 2 Roots 2.1 Root sizes 2.2 Root frequency

[edit] Soil porosity and roots

Porosity refers to visible pores or voids between sand grains, stones or soil aggregates, or created by rooting and biological activity. You should record the dominant type, overall pore frequency and the orientation of the pores (vertical/horizontal etc.).

[edit] Soil pore type

Use the pore type pictures below to help identify the dominanat pore type.

• Tubular (single) are cylindrical, elongated pores e.g. worm channels.
• Tubular (dendritic) are cylindrical branching voids e.g. empty root channels.
• Vesicular/vesicles are ovoid to spherical voids e.g. trapped gas bubbles.
• Irregular are non-connected cavities and chambers of any shape in the soil matrix.
• Interstitial are voids between sand grains and rock fragments.
• Crack are fissures not associated with soil structure.

[edit] Pore frequency

Frequency is determined by estimating the surface area occupied by water or air-filled voids. Use the frequency charts below to identify the most appropriate frequency class.

[edit] Pore orientation

Record whether there is a tendency overall for pores (particularly tubular or crack pores) to run:

• Vertically down through the section.
• Horizontally across the section.
• Randomly at all orientations through the section.
• Dendritic branching from a particular point or level within the section.

[edit] Roots

In buried archaeological soils and sediments it is not only fresh roots, but traces of roots that have since decayed away that are of interest. These root traces may include dendritic void patterns, root impressions on the surface of peds, and the preservation of formaer rooting patterns in iron mottle and concentration patterns.

[edit] Root sizes

Record the presence and frequency of root size classes in the deposit:

• Fine roots less than 2 mm in diameter
• Medium roots 2-5 mm in diameter
• Coarse roots greater than 5 mm in diameter

[edit] Root frequency

Record the number of roots in a 10 cm x 10 cm area of soil.

Root Frequency

Frequency class	Fine roots	Medium and Coarse roots
Few	1-10	1-2
Common	10-25	2-5
Many	25-200	More than 5
Abundant	More than 200