30 



FIELD OPERATIONS OF THE BUREAU OF SOILS, 1912, 



wliile subdrainage is restricted by the com})act subsoil, the surface 

 drainage is good. 



While recognized in this survey as a member of the Rockford series, 

 the material of which is derived from glacial tUl and morainic deposits, 

 this type as mapped includes more or less undifferentiated coUuvial 

 and allu\ial foot-slope material washed from adj acent more elevated 

 slopes occupied by the Underwood loam and the Rockford stony clay 

 loam. 



The Rockford clay type is largely cleared of its native vegetation 

 and used for the production of apples, which has met with success 

 despite the hea\'y subsoil. It is very probable that in those areas 

 where the clay subsoil is most tenacious and lies nearest to the surface 

 the soil would prove well adapted to the pear. 



The following table gives the results of mechanical analyses of 

 samples of the soU and subsoil of the Rockford clay: 



Mechanical analyses of Rockford clay. 



PARKDALE LOAM. 



The soil of the Parkdale loam, to a depth of 12 mches, is a granular, 

 friable, grajdsh-brown to yellowish-brown or light reddish brown 

 loam, containing a considerable number of small iron concretions or 

 pellets or spherically weathered fragments of basaltic rock, similar to 

 those occurring m the soils of the Underwood series. The subsoil is 

 similar to the soil in texture, or it may be a mottled silt loam. It 

 very commonly differs from the surface soil only ui that the pellets 

 are less numerous and the color is Ughter. Material like the subsoil 

 usually extends to a considerable depth below 6 feet. At 20 feet or 

 more below the surface the material, as may be seen in cuts, is a coarse 

 bowlder till, and it is probable that it underhes the entire type. 



In general this soil is permeable and the dramage good, but there 

 are small areas where the internal drainage is deficient. In these 

 places the texture of the soil is heavier than normal, and the effect of 

 the excess moisture has been to bleach the materials, forming areas 

 of hght-colored or ashy-gray soU. 



The Parkdale loam is the prevailing soil of the upper Hood River 

 Valley; that is, that part of the valley above the narrow gorge of the 

 Hood River at Winans. The vaUey floor constitutes a visibly slop- 

 ing plain gradually rising toward the south, bordered on each side by 



