Procedure for Splitting, Describing, and Sampling Cores, and for Determination of Water Content and Bulk Density

Core Splitting

1. after whole core magnetic susceptibility is complete, unwrap core and roll onto a layer of saran wrap on a flat table

2. slide two split PVC tubes under saran wrap and buttress or tape in place

3. carefully cut core with a sharp knife so that the two sides are completely free of one another

4. pull the split PVC tubes away from split cores allowing the core halves to roll onto their backs sides

5. wrap the best preserved half up in two layers of saran wrap; use the plywood to enable you to flip the core into the split PVC tubes to complete your wrapping

6. label the archive half as: Lake Name; Core A (or B, C, etc.), Drive Number (1,2,3, etc.) and Depth of drives in cm (e.g., 100-200 cm); include an up-arrow, and label the top as TOP; write clearly on the core Archive—use masking tape for all labels

7. tape the core into the trough with strips of masking tape so that it cannot fall out if the trough were to roll over

8. repeat for the working half and label it accordingly

Core Description

1. carefully scrape the surface of the core parallel to bedding planes so that you have a clean surface

2. note any obvious sedimentologic breaks and mark them on the core description sheets

3. in the column named UNIT shade the relative changes in darkness/lightness of the sediment

4. in the column named Written Description, include the following:

· Munsell Color- use color book and start on 10YR page

· approximate dominant grain size (gravel, sand, silt, clay)

· note whether massive or laminated, and if laminated, note the thickness of the laminae

· if you can see sand grains, use a handlens and note their roundness

· using the Folk Soring chart decide on the degree of sorting of the layers

· look carefully at the sediment and decide whether or not the unit (or laminae therein) fines upward, coarsens upward, or neither

· note the nature of the lower contact- is it planar, angular or wavy?

· note the abruptness of the lower contact- is it abrupt or gradational? If gradational, over what interval (cm) does the gradation occcur.

Description of Sand Fraction

1. for each layer scrape off a small amount of material and place it on a 75 µm sieve

2. with a squirt bottle (or carefully under a faucet), hose the sediment through the beaker until all that remains are particles that are larger than 75 µm.

3. wash all of these particles into a glass vial, that you have labelled as (sample number, >175 µm)

4. with a pipette draw off about 5 ml of sample and place it on a large, labelled glass slide

5. place slide on microscope and observe the sand grains that are present

6. describe their shape according to the roundness chart above.

7. describe the presence of other grains such as charcoal (shinny, angular, and black), leaves, twigs, etc.) as n (not-present), m (minor), or a (abundant); WRITE THESE VALUES IN THECOLUMN LABELLED SAMPLES TAKEN FOR ANAYLSES IN DESCRIPTION SHEET AS:

· c (charcoal)=n,m, or a

· pf (plant fragments)=n,m, or a

· s (sand)= n, m, or a; rounded/subrounded, etc.

· o (other)= describe

Core Sampling

1. decide upon a sampling interval and indicate where samples are to be obtained on the far right-hand side of the sample description sheet (in the margin on the right side)

2. label enough small snap-cap vials

3. weigh these vials to the nearest 0.001 g on a top loading balance WITHOUT TOPS ON

4. with a clean volumetric sampler, take a 1 cc sample at each of your sampling localities and extrude this into a prelabeled and preweighed vial

5. weigh vial and sample WITHOUT TOPS ON to the nearest 0.001 g on a top loading balance.

6. place vial in a vial holder (block of wood with holes)

7. for pollen samples, cap vials

8. for all other analyses, leave caps off and place in freeze-dryer for 24 hours

9. return and weigh sample and calculate

· % original water content (((wet weight-dry weight)/wet weight))*100)

· dry bulk density (g/cc of sediment)