materials by hand. Generally, No. 4 and No. 200 sieves are used for separating gravel, sand, and fines. . PIONEER TOOLS. Use a pick and shovel or a set of entrenching tools for collecting samples. A hand auger is useful if samples are desired from depths of more than a few feet below the surface. . STIRRER. The spoon issued as part of the mess equipment serves in mixing materials with water to the desired consistency. It also can aid in collecting samples. . KNIFE. Use a combat knife or pocketknife for collecting samples and trimming them to the desired size. .  MIXING  BOWL.  Use  a  small  bowl  with  a rubber-faced  pestle  to  pulverize  the  fine-grained  portion of the soil. Both may be improvised. You could use a canteen cup and wood pestle. .  PAPER.  Several  sheets  of  heavy  paper  are needed for rolling samples. . PAN AND HEATING ELEMENT. Use a pan and heating  element  to  dry  samples. c  SCALES.  Use  balances  or  scales  to  weigh samples. The  Unified  Soil  Classification  System,  as  shown in  appendix  V,  considers  three  soil  properties:  (1) percentage of gravel, sand, or fines, (2) shape of the grain  size  distribution  curve,  and  (3)  plasticity.  Other observed properties should also be included in the soil description,  whether  made  in  the  field  or  in  the laboratory. The following descriptions represent some of the typical characteristics used in describing soil: . Dark brown to white or any suitable color shade description l  Coarse-grained,  maximum  particle  size  2  3/4 inches,  estimated  60-percent  gravel,  36-percent  sand, and 4-percent fines (passing through No. 200 sieve) l  Poorly  graded  (gap-graded,  insufficient  fine gravel) .  Gravel  particles  subrounded  to  rounded,  or predominately   gravel .  Nonplastic . Mostly sand with a small amount of nonplastic fines  (silt) c Slightly calcareous, no dry strength, dense in the undisturbed  state VISUAL EXAMINATION Visual  examination  should  establish  the  color,  grain size, grain shapes (of the coarse-grained portion), some idea  of  the  gradation,  and  some  properties  of  the undisturbed  soil. Color is often helpful in distinguishing between soil types, and with experience, one may find it useful in identifying the particular soil type. Color may also indicate the presence of certain chemicals. Color often varies with moisture content of a soil. For this reason, the moisture content at the time of color identification should be included. Some of the more familiar color properties  are  listed  below. . Generally, colors become darker as the moisture content increases and lighter as the soil dries. .  Some  fine-grained  soils  (OL,  OH)  with  dark drab shades of brown or gray, including almost black, contain  organic  colloidal  matter. . In contrast, clean, bright looking shades of gray, olive green, brown, red, yellow, and white are associated with  inorganic  soils. l  Gray-blue  or  gray-  and  yellow-mottled  colors frequently  result  from  poor  drainage. l Red, yellow, and yellowish brown result from the presence  of  iron  oxides. . White to pink may indicate considerable silica, calcium carbonate, or aluminum compounds. The  maximum  particle  size  of  each  sample considered should always be estimated if not measured. This establishes the upper limit of the gradation curve. Gravels range down to the size of peas. Sands start just below this size and decrease until the individual grains can  barely  be  seen  by  the  naked  eye.  The  eye  can normally see individual grains about 0.05mm in size or about the size of the No. 200 screen. Thus silt and clay particles (which are smaller than this dimension) are not detected  as  individual  grains. While the sample for grain sizes is being examined, the  shapes  of  the  visible  particles  can  be  determined. Sharp edges and flat surfaces indicate an angular shape; smooth, curved surfaces are associated with a rounded shape.  Particles  may  not  be  completely  angular  or completely  rounded.  These  particles  are  called 16-16