Ch. 2] TIME 43 



Parent material functions or lithof unctions: 



s = f(p)d,o,r,t 



Soil properties are related to parent material under conditions of con- 

 stancy of cl, o, r, t. 



Topography functions or topofunctions : 



s = f(r)d,o, P ,t 



Soil properties are correlated with topographic and drainage features 

 when cl, o, p, t are constant. 



Climatic functions or climof unctions : 



f(fil)o. 



r,p,t 



Soil properties are related to climatic variables under conditions of 

 constancy of o, r, p, t. 



Organism functions or biof unctions : 



S = f(o) c i trt p,t 



Soil properties are dependent on organic species. These functions deal 

 with relationships between soil properties and organisms when cl, r, p, t 

 are held constant. 



The soil-forming factors cl, o, r, p are multiple factors and yield groups 

 of functions. 



Soils have many properties: s 1? s 2 , s 3 , s 4 , etc. All properties taken 

 together constitute a collection, assemblage, or ensemble of properties 

 which is the soil. If the ensemble of s values is designated by the 

 symbol E( 8 ), 



Soil = E is) = f(cl, o, r, p, t) (2) 



Just as each individual s property is a function of the soil-forming 

 factors, so is the entire ensemble dependent on cl, o, r, p, and t. In 

 practice, the variations of the ensemble are recognized as profiles, soil 

 types, soil series. In accordance with the five pedologic functions, the 

 ensembles may be arranged in five sequences: chrono-, litho-, topo-, 

 climo-, and bio-sequences. In contrast to equation (1), equation (2) 

 is qualitative since "soil" cannot be assigned a single numerical value. 



Time (Chronofunctions and Chronosequences) 



The rate of soil formation varies widely. It is often stated that 

 it takes thousands of years to produce one inch of soil. As judged 

 from weathering of dated buildings and tombstones, this estimate is 



