Sorting Flotation Samples

General Procedures

Preparing to Sort

1. Copy complete sample information onto lab form. If something is not entirely legible, ask T.A. or instructor.
2. Select appropriate geological sieve screens, and, making sure they are free of debris or others’ samples, stack them in order of descending mesh size. Always use 2.0 mm sieve and 0.7 mm sieve.
3. Check accuracy of scale with known weight; if off, re-calibrate.
4. Weigh entire sample in tared container and record weight on Laboratory Analysis Form to 0.01 gram (i.e., 11.11 g).
5. Place sample into top screen and shake/tap material through screens as demonstrated by T.A. or instructor.
6. Over ceramic basin, transfer screen material to pre-tared weighing dish; weigh, double check, then record weight on lab form.
7. Over ceramic basin, transfer material to tin container, label with provenience information and geological sieve mesh size, and close lid tight.
8. Place all tins in ziplock bag and write provenience information on the bag.

Sorting

1. Pour manageable amount into sorting tray.
2. By passing one object at a time into the field of vision, sort material from geological sieve screens 2.0 mm and larger into groups of “things that look different at ca. 10X magnification,” making little piles along side of sorting pan or removing particles of the various groups to separate containers on lab counter. Consult T.A. or instructor for confirmation of categories.
3. Count and weigh (to nearest 0.01 g) the various types of materials larger than 2.0 mm in size, and record counts and weights on Laboratory Analysis Form. At this point, all wood from the various geological sieves larger than 2.0 mm gets combined, as do all like particles belonging to the other categories (i.e, all hickory  nutshell larger than 2.0 mm, all corn kernels larger than 2.0 mm, all persimmon seed fragments larger than 2.0 mm, etc.). Label each tin (writing with pencil on the paper lid) or gelatin capsule (writing with pencil on a small strip of acid-free paper that fits inside) with the provenience information and the archaeobotanical category (i.e., “wood”, “acorn shell”, “unknown”).
4. From geological sieves with mesh smaller than 2.0 mm, extract acorn shell, cultigens, seeds, and previously non-represented items (e.g., pecan shell is frequently not represented in the larger-than-2.0 mm screens) and separate into groups. This will leave a large “residue” category containing unsorted wood, nutshell, clay balls, rootlets, etc.
5. After seed types, cultigen types and other categories have been confirmed by T.A.or instructor and residue has been checked, weights and counts can be recorded on the Laboratory Analysis Form.  The “Residue” weight includes all residual material smaller than 2.0 mm and down to (and including) the 0.7 mm sieve.
6. Measurements are necessary for many seeds, corn cupules, cucurbit rind, and some other items. Check with T.A.

    

Reports

Papers should adhere to scholarly standards of style, grammar, and construction. Each paper should include a bibliography and every source should be cited at least once in the text. Any scholarly style of citing references is acceptable-just be consistent. When ideas and models, as well as direct quotes, of others are used, the authors must be cited. If you are not already familiar with an academic style of citation, may we suggest that you consult the style guide of American Antiquity.

     

Written by: Katherine M. Roberts