# EGE 3083 Sedimentology: Energy of the System

### Questions:

Introduced to the concepts of grain size analysis and techniques for analyzing grain size through class lecture and textbooks readings. Time in class is spent ensuring that students understand the use of the phi system of grain size classification, which is used to create log-probability plots.

Statistical concepts of particular relevance to grain size analysis are covered in class; discussion focuses on how the central tendencies (mean, mode, median), skewness andkurtosis of grain size distribution (Folk, 1959) have been interpreted by sedimentologist. The construction of histograms is reviewed and probability plots are introduced as a way of presenting and interpreting grain size data.

a. Weight dried 100 g sample and transfer into 1000 ml beaker
b. Add 100 ml of 30% hydrogen peroxide (H202)
c. Heat the sample on the hot plate or sand bath until the volume reduced to half. Stir well the mixture from time to time.
d. Add distilled water when necessary to control reaction and reduce bubble
e. Add another 150 ml of H202
f. Stir well the mixture until no bubble is produced
g. Remove the beaker from hot plate/sand bath and leave for at least one hour.

Observation illustrate the close-up of hand specimens of your samples. Describe the followings:
a. Clast roundness
b. Clast sphericity
c. Sorting

2. Results
a) Complete the following tables:
 Table 6-8 (See Section 5.4; Silt and Clay)
 Table 9-11 (Note: See Section 5.5; Sand particles)

b) Construct the following graphs (for each samples):
 Particle size analysis distribution curves
 Histogram
 Frequency curve
 Cumulative percent probability frequency scale
 Kurtosis vs. skewness
 Skewness measure vs. sorting
 Skewness vs. standard deviation
 Log (Ø) probability plot of cumulative grain size frequency distribution

c) Based on particle size distribution curve, calculate the followings:
 Median grain size (Graphic mean)
 Sorting/standard deviation
 Skewness
 Kurtosis
 Variance

Discussion a. Explain and interpret ALL your observation, graphs, and calculations
b. For analysis, discuss any experimental error, strengths or weaknesses of the design, and relationship to your objective.
c. Answer, discuss and comment the following question:

i. What factors in these methods might affect accuracy?
ii. What factors might affect precision?
iii. What do the data indicate about the energy of the system?
iv. What is a likely environment of deposition of your sample? Justify it.

d. Discuss Visher’s hypotheses and relate with your results (Refer reference no. 2)
e. You are encouraged to explain extra facts/points, etc. in your discussion.