the slots and then bending sharply over the thumb nail. The edges of slots are 

 sanded lightly. 



The templet, with log inserted, as in Figure 3-1, is placed on the table in 

 the most convenient position and then fastened to the table by Scotch drafting 

 tape. The templet will now hold the log firmly during the course of plotting. 



The diagonal slot at the top is for outlining in pencil or ink the areas to 

 be colored for minor constituents. Coloring is also done through the slot. The 

 second slot is used for filling in the rectangular graph for grain sizes. 



The rectangular window is used for coloring thick, homogeneous lithologic 

 units such as gray shales. Although the inked symbols for accessory minerals 

 are usually drawn freehand, cutouts of the right size and shape can be made in 

 the templet in order to achieve more uniformity in the symbols. 



The minor-constituents slot is cut diagonally across 40 feet on the strip log. 

 This approximately 45-degree angle has the advantage of exact duplication 

 without a protractor. 



Grain-Size Graph 



A graph indicating the average grain size of clastic and carbonate rocks 

 according to the classification coarse, medium, fine or very fine may be made 

 without sacrificing description space on the log. Along the right side of the 

 color column four light pencil lines are drawn parallel to the column and spaced 

 1/30 inch apart. The line nearest the column represents fine grains, the farthest 

 out, coarse. When the samples are run, the graph is filled in with medium-gray 

 pencil. Inked descriptions start at the edge of the column, disregarding the solid 

 shadow graph, which will be discernible in spite of the lettering. The pencil 

 guide lines are drawn with a steel straight edge the full length of the strip before 

 the work is begun. At intervals where the graph is not used, the guide lines are 

 erased. The templet may be cut as shown in order to draw the graph without 

 guide lines. A grain-size graph is shown in Figure 3-5A. 



Lettering of Logs 



The order of descriptive terms on a log has been mentioned. The lettering 

 should be in black waterproof ink. Various pens are satisfactory, such as the 

 crow quill or Hunt No. 104. The latter is somewhat better because the point is 

 more rigid, though equally fine. The log is somewhat more legible and dis- 

 tinctive if the rock name or its abbreviation is in vertical letters and the de- 

 scription in slant letters. Thus the descriptions of two or more rocks on a single 

 line are more distinct. 



The ink used in fine pens should be thinned with distilled water to which 

 a few drops of ammonia have been added. A moist sponge in a cup is convenient 

 for a pen wiper, and there is no danger of damaging the point as with a cloth 

 wiper. 



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