6 BULLETIN 512, U. S. DEPARTMENT OF AGRICULTURE. 
Terracing affords the best means of conserving the hillside soils” 
against the washing due to heavy rains. 
A field trip was made by the writer through the States of North 
Carolina, South Carolina, Georgia, Alabama, and Mississippi for 
the purpose of studying the nature, causes, and effects of erosion, and 
more particularly the method of preventing erosion by means of 
terraces. Surveys of terraced fields which afford typical examples 
of every form of terrace in use were made with a view to deducing 
from a close study of the field data comprehensive and definite in- 
structions for the design and construction of adequate and efficient 
systems of terraces. It was found that a great diversity of opinion 
exists among the landowners as to the best form of terrace and in 
the rules employed in planning a system of terraces. However, this 
difference of opinion, in most cases, could be attributed directly to 
varying conditions of soil and topography or to differences in 
farming methods. 
The subject of the proper methods of terracing was cheeteed at 
length with experienced farmers—men who are pioneers in the prac- 
tice of terracing and who are interested vitally in the preservation 
of their lands for themselves and their posterity. The deductions 
and conclusions reached are the result of an endeavor to treat from 
an engineering standpoint the information obtained from actual 
observation of field conditions in connection with the data derived 
from field surveys and the advice and opinions of the best informed 
and most experienced farmers. 
DEFINITION AND CLASSIFICATION OF TERRACES. 
As applied to the protection of farm lands, a terrace is any ar- 
rangement or disposition of the soil the object of which is to retard 
the rapid movement of surface water and thereby arrest the process 
of erosion. According to the earliest practice, terracing consists of 
building land up in a series of level areas resembling stair steps, the 
interval between the risers being horizontal and the riser itself being 
vertical or nearly so. This type of terrace has long been used ex- 
tensively in Europe and China and is used to a great extent on the 
steeper lands in the United States. It is known generally as the 
level bench terrace, but to avoid confusion in the use of the term 
“level” it will be referred to in this paper as the horizontal bench 
terrace. Strictly speaking, this is the only true terrace, but the word 
“terrace ” in this country is applied also to ridges of soil thrown up 
and located in such manner as to prevent the rapid flow of water 
down a slope. This type of terrace will be referred to in this paper 
as the ridge terrace to distinguish it from terraces of the bench type. 
The following classification (fig. 1) of terraces shows the various 
forms of bench and ridge types. 
