Field Analysis:How Stones

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Contents 1 How to record stones 1.1 Dominant stone size 1.2 Stone abundance 1.3 Stone rounding 1.4 Stone distribution and orientation 1.5 Other characteristics

[edit] How to record stones

Stoniness refers to the mineral fraction larger than 2 mm diameter.

[edit] Dominant stone size

Size refers to longest dimension of the stones. The dominant stone size should be recorded though where necessary additional notes about the range of sizes present may be made in the general comments box.

Stone size

Fine pebbles	2-6 mm
Medium pebbles	6 mm-2 cm
Coarse pebbles	2-6 cm
Cobbles	6-20 cm
Stones	20-60 cm
Boulders	more than 60 cm

[edit] Stone abundance

Record the frequency of stones (greater than 2 mm) by estimating the surface area they cover in the section. Use the frequency charts below to help identify the right abundance class.

[edit] Stone rounding

It is possible that different stone types or sizes will be more or less rounded reflecting different hardness or different depositional histories. If so record each group separately in general comments. N.B. rounding refers to the rounding off of sharp edges, not how spherical a stone is. Flattened stones may also be rounded.

[edit] Stone distribution and orientation

Record clustering and/or banding of stones, increasing or decreasing stone frequency with depth.

Also, note if there is a preferred orientation of the long axis of the stones. Are they tending to lie horizontally or vertically within the deposit. Are there signs of imbrication, whereby one stone is partially overlain by the next all with their long axes pointing the same way?

[edit] Other characteristics

Note the number and diversity of different stone types (lithologies), and also where possible make a note of whether these are found locally or not. For example, are they found on or around the site, or might they be found elsewhere in the catchment.