GUIDE TO SORTING FLOTATION SAMPLES

Paleoethnobotany Laboratory

Washington University in St. Louis

General Procedures

A. 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.

B. 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.

Tips:

            -use pencil

            -wash hands before handling samples

            -remember to tare the scale!!!!!

            -sum screen weights before sorting. Differences between initial totals and sums

                     exceeding 0.5 grams may be cause for concern.

            -make sure tins, screens and other containers are free of debris. Use dry brush to

                     remove debris.

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