. Bulletin of the Department of Agriculture. Agriculture; Agriculture -- United States. PREVENTION OF EROSION BY TERRACING. 7 The bench type of terrace is subdivided into two classes, the hori- zontal and the sloping, the essential difference between the two being shown clearly by figure 1. Practically all terraces of the bench type are level, which means that they have no fall along the direction of their length to drain off surface water to the edges of the field or to an outlet channel. The ridge type of terrace is subdivided into two general classes, the graded and the level, dependin
. Bulletin of the Department of Agriculture. Agriculture; Agriculture -- United States. PREVENTION OF EROSION BY TERRACING. 7 The bench type of terrace is subdivided into two classes, the hori- zontal and the sloping, the essential difference between the two being shown clearly by figure 1. Practically all terraces of the bench type are level, which means that they have no fall along the direction of their length to drain off surface water to the edges of the field or to an outlet channel. The ridge type of terrace is subdivided into two general classes, the graded and the level, depending upon whether it has fall in the direction of the terrace to carry off the surface water. Graded and level-ridge terraces are subdivided further into two classes with re- spect to breadth of base, namely, the broad-base and the narrow- base forms. The broad-base graded terrace is subdivided again with [Horizontal Bench . BENCH TYPE' (Sloping Bench terraces! (Narrow Base [Level- ridge TYPE - (Broad Base (Narrow Base. [Graded. iUmybrm Gr^de \/ariabh Grade Fig. 1.—Classification of terraces. respect to grade, the uniform-graded and the variable-graded ter- races. Figure 2 shows actual profiles taken on terraced fields and illustrates the various types. THE BENCH TERRACE. Bench terraces, as stated, are of two classes—the horizontal and the sloping—-depending upon whether the bench is horizontal or sloping. There are not many good examples of the true horizontal-bench terrace in this country, while the sloping-bench terrace is quite common. (See fig. 2-A, and PI. Ill, fig. 2.) This is due to the fact that the horizontal bench is developed from the sloping bench by the gradual movement of the soil down the slope, owing to erosion, and to the use of the hillsidi plow, which always throws the soil down the slope. The time required for the leveling down of a sloping bench. Please note that these images are extracted from scanned page images that may have been digitally enhanced f
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