8 BULLETIN 512, U. S. DEPARTMENT OF AGRICULTURE. 
depends upon the amount of soil moved down the slope each year and 
upon the vertical distance between the terraces. It is necessary to 
maintain a shoulder of earth at the lower side of the bench for slop- 
ing-bench terraces, and it is advisable that this be done for hori- 
zontal-bench terraces, for the purpose of retaining that portion of 
the rain water which does not sink into the soil. This shoulder and 
the lower side of the embankment-should be seeded to grass. (See 
SE CO OS RR PE Se 
fas | ee OR TES A Ss 
En Ee ee a Coe 
, aaa eee Ee See 
os (ata A DT A ces oe es 
p= a ES PR Ve 0 
9: 50’ 100’ 150° 
Fig. 2.—Actual profiles of terraced fields, taken across terraces. 
side of the embankment and protects both the shoulder and the em- 
bankment from erosion due to surface water overtopping the shoul- 
der. The leveling-down process mentioned above sometimes is con- 
tinued until the slope of the bench isreversed. Thus, the water falling 
on the bench will flow to the foot of the embankment above. In this 
case no shoulder will be required to prevent the water from washing 
over and eroding the embankment. 
