ballpoint ink on plastic strip (plastic orange flagging commonly used by
surveyors). Some information may be preprinted by rubber stamp on the
plastic strip using indelible laundry ink. The advantage is that the
label can be stored in the bag with the wet sample without the label
deteriorating or the information washing or wearing off.
4.27 SIZE ANALYSES
Three common methods of analyzing a beach sédiment for size are:
Visual comparison with a standard, sieve analysis, and settling tube
analysis.
The mean size of a sand sample can be estimated qualitatively by
visually comparing the sample with sands of known sizes. Standards can
be easily prepared by sieving out selected diameters, or by selecting
samples whose sizes are already known. The standards may be kept in
labeled transparent vials, or glued on cards. If glued, care is necessary to ensure that the particles retained by the glue are truly représentative of the standard.
Good, qualitative, Visual estimâtes of mean size are possible with
little previous expérience. With expérience, such Visual estimâtes
become semiquantitative. Visual comparison with a standard is a useful
tool in reconnaisance, and in obtaining intérim results pending a more
complété laboratory size analysis.
4.271 Sieve Analysis. Sieves are graduated in size of opening according
t° the U.S. Standard sériés. These standard sieve openings vary by a factor of 1.19 from one opening to the next larger (by the fourth root of 2,
or quarter phi intervals), e.g., 0.25, 0.30, 0.35, 0.42, and 0.50 millimeters (2.00, 1.75, \.5O, 1.25, 1.00 phi). The range of sieve sizes used,
and the size interval between sieves selected can be varied as required.
Typical beach sand can be analyzed adequately using sieves with openings
ranging from 0.062 to 2.0 millimeters (4.0 to -1.0 phi), in size incréments mcreasing by a factor of 1.41 (half-phi intervals).
Sédiment is usually sieved dry. However, for field analysis or for
size analysis of sédiment with a high content of fine material, it may be
useful to wet-sieve the sédiment. Such wet-sieve analyses are described
by (e.g., Lee, Yancy, and Wilde, 1970, p. 4).
Size analysis by sieves is relatively slow, but provides a widely
accepted standard of reference.
4’272 Settling Tube. Spherical sedimentary particles settle through
wa er at a speed that increases as the particle weight increases. Since
snecifîc
T^s“y near quartz, particle size is proportional to particle
Christêns»
velocity can be used to measure size. (e.g., Colby and
shows fâîî C. 5 i z®lgler and Giu. 1959; and Gibbs, 1972.) Figure 4-31
ocity for quartz spheres as a function of température.
4-26
surveyors). Some information may be preprinted by rubber stamp on the
plastic strip using indelible laundry ink. The advantage is that the
label can be stored in the bag with the wet sample without the label
deteriorating or the information washing or wearing off.
4.27 SIZE ANALYSES
Three common methods of analyzing a beach sédiment for size are:
Visual comparison with a standard, sieve analysis, and settling tube
analysis.
The mean size of a sand sample can be estimated qualitatively by
visually comparing the sample with sands of known sizes. Standards can
be easily prepared by sieving out selected diameters, or by selecting
samples whose sizes are already known. The standards may be kept in
labeled transparent vials, or glued on cards. If glued, care is necessary to ensure that the particles retained by the glue are truly représentative of the standard.
Good, qualitative, Visual estimâtes of mean size are possible with
little previous expérience. With expérience, such Visual estimâtes
become semiquantitative. Visual comparison with a standard is a useful
tool in reconnaisance, and in obtaining intérim results pending a more
complété laboratory size analysis.
4.271 Sieve Analysis. Sieves are graduated in size of opening according
t° the U.S. Standard sériés. These standard sieve openings vary by a factor of 1.19 from one opening to the next larger (by the fourth root of 2,
or quarter phi intervals), e.g., 0.25, 0.30, 0.35, 0.42, and 0.50 millimeters (2.00, 1.75, \.5O, 1.25, 1.00 phi). The range of sieve sizes used,
and the size interval between sieves selected can be varied as required.
Typical beach sand can be analyzed adequately using sieves with openings
ranging from 0.062 to 2.0 millimeters (4.0 to -1.0 phi), in size incréments mcreasing by a factor of 1.41 (half-phi intervals).
Sédiment is usually sieved dry. However, for field analysis or for
size analysis of sédiment with a high content of fine material, it may be
useful to wet-sieve the sédiment. Such wet-sieve analyses are described
by (e.g., Lee, Yancy, and Wilde, 1970, p. 4).
Size analysis by sieves is relatively slow, but provides a widely
accepted standard of reference.
4’272 Settling Tube. Spherical sedimentary particles settle through
wa er at a speed that increases as the particle weight increases. Since
snecifîc
T^s“y near quartz, particle size is proportional to particle
Christêns»
velocity can be used to measure size. (e.g., Colby and
shows fâîî C. 5 i z®lgler and Giu. 1959; and Gibbs, 1972.) Figure 4-31
ocity for quartz spheres as a function of température.
4-26