00 



90 



80 



70 



60 



50 



40 



30 



20 



10 



10 



I .1 



05 



I'll 

 Dl A M ETER IN MM. 



pebble I g ran 



iv.crs. 

 ss. 



crs. 

 ss. 



med. 

 ss. 



A 

 Md-.750 

 Q, -.500 

 Q 3 -.820 

 S -I- 28 

 S k -.73 



fine lv.fi ne 

 ss. ss. 



B 

 Md -.265 

 Q, -.096 

 Q 3 -.700 

 S ~ 2.70 

 Sk -.9 6 



crs. I med 

 sill silt 



.01 



fine 

 silt 



•005 



v. f i n e 

 silt 



.001 



lay 



c 

 Md -.120 

 Q, -.100 

 Q 3 -.154 

 S -1-24 

 Sk -107 



Figure 6-3. Cumulative-frequency curves and statistical parameters of three different sands. 



The histogram is the simplest type of diagram that shows graphically the 

 results of a size analysis. Normally the size intervals are plotted along the hori- 

 zontal axis and the weight percentage of each size interval along the vertical 

 axis. Because the range of grain diameters is not equal for each size interval, 

 a logarithmic scale is used along the horizontal axis; and if the Wentworth 

 scale is used, each size interval will be equal width. Figure 6-1 is the histo- 

 gram based on data recorded in Table 6-II. 



The cumulative-frequency curve (fig. 6-2) is plotted on semi-logarithmic 

 paper, with the logarithmic scale representing the diameter of the grains in 

 millimeters and the arithmetic scale representing the cumulative-weight percent- 

 age. The cumulative-frequency curve is prepared by plotting opposite the 

 diameter of each screen opening the weight percentage that would have been 

 retained by the screen if all screens larger had not been used. Figure 6-2 is the 

 cumulative-frequency curve plotted from the data in Table 6-II. 



The cumulative-frequency curve emphasizes the continuous distribution of 

 sizes and has the advantage that statistical data may be obtained directly from 



100 



