A PRELIMINARY REPORT ON CLAYS OV VLoRIDA 253

which it underlies, as well as the character and thickness of the overburden or material overlying the clay. It is also desirable to know if the clay is of uniform quality throughout the deposit and, if not, the character and extent of its variation. This can best be done by means of an auger, either a "prospector's auger" or an ordinary wood auger. These should be at least two inches in diameter, and should be attached to a shaft or pipe about three-fourths of an inch in diameter. The pipe can be most conveniently handled if it is cut into lengths of about three feet each, so that as the boring increases in depth new joints may be added. A T-joint should be attached to the top so that the auger may be rotated. Borings forty or fifty feet in depth may be conveniently made with apparatus of this type.
 In an area to be prospected, borings should be made about every fifty feet in each direction. A plot, or sketch map, should be made, showing the locations of the holes and an accurate record should be kept of the thickness, character and sequence of the formations encountered.
 In addition to an intelligent record being kept of each hole, samples of the materials taken from the boring should be kept and properly labeled. In taking samples of borings of this type great care must be exercised so that material falling into the hole from above, or scraped off from the upper walls as the auger is withdrawn, is not included with the samples.
 The samples from each boring, and particularly those from the clay stratum, should be carefully examined, in order to note any apparent changes in character, laterally or vertically, and to determine its thickness from place to place.
 Samples taken by an auger are satisfactory for determining the thickness and extent of a clay deposit and any variations which may exist in it. For the determination of the physical properties of the clay, however, larger and cleaner samples are desired than is usually possible to obtain with an auger. Digging a pit is the most satisfactory method of taking a clay sample. A sample of any size desired can then be obtained and a detailed inspection of the deposit made. For a large deposit several pits should be dug.
 The location of a clay deposit, with respect to transportation, markets, fuel, etc., should be given very careful consideration. A clay suitable only for structural materials would be of little value unless located very near a line of transportation and where there is an ample supply of fuel.