Appendix: Particle Size Analysis
Wet Sieving Procedure
Equipment needed: Metal tray, riffle box, oven set to 100o
C, weight balance, bucket, stirrer, 50g/l sodium hexametaphosphate, stainless
steel sieves, O-rings, sieve shaking apparatus.
A sample of >400g is needed for wet sieving -depending
upon the maximum clast size. ?
Samples need to be dried in the oven (at least 70o C) before
Split the sample using the riffle box in order to extract a
subsample for the laser granulometer. The sample may need to be split a number
of times in order to extract a c.5g subsample. ?
Once the subsample is extracted, amalgamate the remaining
Weigh the dried sample to 2 decimal places using the coarse
balance 1. ?
Add the sample to a clean bucket and cover with water from
the tap. ?
Add 100ml 50g/l Sodium hexametaphosphate solution (breaks
the sediment down). ?
Stir the sample for a few minutes. ?
Select sieves ranging from 16mm (-4ø) mesh diameter to 250?m
(2ø) mesh diameter. Around 8 to 9 sieves are
10. Stack the
sieves in order from highest mesh diameter to lowest (250?m or 2ø should be at
the bottom of the stack). Place a rubber O-ring between each sieve. ?
11. Place the
base pan on the sieve shaker with the outlet/tube facing into the sink. ?
12. Place the
sieve stack onto the base pan. Ensure there is an O-ring between the final sieve
and the base pan and that the sieve stack is attached securely. ?
pour the sample from the bucket into the top of the sieve stack. Ensure that
the portion <250 ?m is pouring out of the outlet and into the sink. Wash the bucket ?out with water until it is clean. ? 14. Attach the lid of the sieve shaker and secure it using the twin-nuts. The lid should be fitted with a tube attached to a tap. ? 15. Ensure the lid is securely fastened and turn on the tap. There is an attachment within the sieve shaker lid that will spray the sample with water. Ensure the water is running freely through the sieve stack and into the sink. ? 16. If the water is running freely, switch on the sieve shaker. The amplitude should be set to at least 2 and the sieve shaker should run for 5 to 10 minutes, until the water flowing out the sieve stack runs clear. ? 17. When the shaking stops, turn off the tap and allow all water to pass through the sieves.
18. Remove the
lid, remove each sieve and place into the oven at c.80o C. Check each sieve is
clean before removing from the sieve stack and ensure that the O-ring is
removed before the sieve is placed in the oven. ?
19. Dry the
sieves containing sediment at 80o C overnight. ?
20. Once dry
weigh the portion of the sediment that is retained on each sieve. ?