Analysis of a hardpan: Cal.: 

 Sand 37 A 

 Silt (a) 30 

 Silt (e) 14 

 Clay 8 



Dust soils are much ground up and worked over by shifting v/inds 

 and is worn very fine. It causes much trouble to irrigatorn in Washing- 

 ton thru its tendency to suddenly become impervious. Dust soils are 

 peculiar and interesting soils. They contain a relatively large amount 

 &&&&& of very fine silt which is all of a size, and layers very close- 

 ly. Hilgard suggests that the small amount of clay which is present acts 

 somewhat like the linseed oil in putty. 



j[. Iron rust sands arid other Hardpans. 



The true iron rust and other hardpans are of a different ori- 

 gin from the above hardpans. They occur on the northern German plains 

 and in the Baltic region. There is usually a bed of coarse sand; under- 

 neath thin a.t a depth of 2 to 3 feet is a layer of hard rusty material. 

 Humic acid gets down and form hard layers by acting as a glueing cement 

 which cements 1 together the particles, making a hard compound. It occurs 

 in cold countries and is best in damp climates; the upper soil bleaches 

 to a lead s-md, and all of it is thoroly worthless and useless. It is 

 hard to reforest on, and is a great obstacle to the forer-ter. To get 

 rid of this hardpan tremendous steam plows are used in Europe, with a 

 double engine on each side of the plow. It breaks up the hardpan, but 

 if the action is not repealed the hardpan glues together again in a few 

 years. 



G) Composition of Soils 



is the soil made of? "3iat are its consituents? 



si. Composition of the earth's crust in general 



The earth is estimated to be composed of : 7% air and water 



93^ solid. 



The cruot at a point six miles down is supposed to be about as 

 follows: 



5Q/5 0. It has also been estimated that the crust 



27 Si in this six miles is composed as follows: 



5.5 ye 15 



4 Ca 6 Fe oxides 



4 MgO 



5 CaQ 



I>. Principal minerals in the soil: 



1) quartz: forms practically all of our sands, the larger part 

 of our silts, and in the form of a fine flour (very fine silt) makes 

 materials closely resembling clay. Quartz is very constant in soil, and 

 is not affected by weathering: it is persistent and uniform. In the 

 form of Bind nd silt it forms the principal body of soils and of sands, 



and olays. 



2) Feldspar: there are two varieties of feldspar: 



Orthoclase: potash, good for soil;monoclinic. 

 Plagioclase: soda (lime); triclinic. 

 Potash feldspars are the most common, but are none too resistant 



