11. Color . Based on the Geological Society of America Rock-Color 

 Chart. For those samples where color was not determined in the field, 

 the sample was moistened in the laboratory for a color determination. 



12. Odor . A qualitative description of any noticeable odors. 1 



o 



13. Wet Density ( lb s/ft ) . Density measured to the nearest tenth 

 of a pound as determined by means of a "Mudwate" hydrometer. 



U4.. Rigidense (mm) . Determined by means of a Rigidense instrument 

 and measured to the nearest millimeter. This test is no longer 

 performed. 



15. Maximum Porosity {%) . The percentage of pore space in the 

 total volume of the uncompacted sample not occupied by solid matter; 

 computed by the formula: 



P = 10U(V - -) 

 T 



where P is the porosity in percent, V is the bulk volume, and v is the 

 aggregate volume of the grains. 



16. Minimum Porosity (%) . The percentage of pore space in the 

 total volume of the compacted sample not occupied by solid matter; com- 

 puted by the same formula as given in maximum porosity. 



17. Water Content {%) . Ratio of the weight of water in a sample 

 to the weight of the dried sample expressed in percent. 



18. Organic C arbon Content {%) . Based on the Schollenberger method 

 of organic carbon determination by reduction of chromic acid. 



19. Size Analysis and Statistical Measures . Sample size fraction 

 values are based on dry weight and given in phi (/) units to the nearest 

 whole percent. An American Instrument Company sieving machine and U.S. 

 standard sieves were used for determining sand and larger size fractions 

 (>l/l6 mm). The pipette method, based on Stokes Law (for computing 

 settling rates of spherical particles), was used to determine silt size 

 (1/16 to 1/12^6 mm) and clay size particles (1/1256 to 1A096 mm). Any 

 colloidal material (<L/U096 mm) was included with the clay. 



QD^ - (phi quartile deviation). Is that statistical param- 

 eter which is a measure of one half of the spread of the 

 quartiles and is expressed in phi units with the given 

 value computed from the formula: 



QD0 7 



hi - \i 



183 



