32 



FIELD OPERATIONS OF THE BUREAU OF SOILS, 1912. 



The folloA\diig table gives the average results of mechanical analyses 

 of the soil and subsoil of this type: 



Mechanical analyses of Parkdalc loam. 



HOOD SILT LOAM. 



The soil of the Hood silt loam is of light-gray or yellowish-gray 

 color, excepting in a few poorly dramed areas, where the color ranges 

 from dark gray to nearly black. The soil is predominantly a silt 

 loam, the silt content, however, being rather low and replaced to a 

 large extent by very fine sand. In many localities it closely ap- 

 proaches a loam or silty, fine sandy loam in texture, and some un- 

 differentiated bodies havmg a light loam or heavy fine sandy loam 

 texture occur. The variation in texture is, however, not %vide, and 

 in general appearance, structure, and relation to agriculture the type 

 is remarkably uniform. A few concretions or pellets occur in places, 

 and where the tyjDC adjoins the Underwood loam there has been 

 here and there an admixture of material washed from the slopes 

 occupied by the latter soil. 



The subsoil is a loam or silt loam and very much like the soil in 

 texture and color, but there are a number of places m the Hood River 

 Valley where the subsoil is extremely compact, bemg locally known 

 as a hardpan. This compact material is frequently slightly cemented, 

 and causes considerable trouble in handlhig the orchards, as it not 

 only hhiders the internal dramage of the soil, but prevents the normal 

 development of the tree roots, resulting m a decrease m the vigor 

 and productiveness of the trees. 



In depth the soil mass is subject to more or less iiTegularity. In 

 the Wliite Salmon River Valley, so far as could be determined, it rests 

 directly upon the underl}dng basalt, wliich may occur at any depth 

 between 6 and 100 feet. In the Hood River Valley the soil is appar- 

 ently underlaui in places both by deposits of glacial till and by strlita 

 of an incoherent, yeUowish-brown sand, though neither of these 

 formations seem to occur witliin 10 or 15 feet of the surface. In the 

 areas of the deeper deposits the substratum underlying the subsoil 

 usually consists of compact, stratified fine sand, fuie sandy loam, or 

 more frequently of finer sediments of silty clay loam or silty day 

 texture. Both soil and subsoil material are free from gravel, bowlders, 

 or other rock fragments, except in a few localities adjoining other soil 



