The approach of Horton is used hy Kirkby to explain the occurrence of 
certain erosion features on a hillslope (Kirkby 19^9)• ’’There should therefore 
he a line of channel heads across a hillside, each channel head being at the 
critical distance from the divide. Falling from this line there should be a 
set of many subparallel rills, or shoe string gullies, covering the hillside". 
The rills may.‘develop into a few gullies lower down the slope. The width of a 
belt of no erosion and the soil erosion features on the slope are related to 
the runoff accumulated with distance from the divide. (Leopold, 1969 ) 
A general inventory of soil erosion in an area in Idaho, USA, is given 
by Leopold ( 1964 ). The distribution of surface erosion and linear erosion 
on slopes of different steepness corresponds with a curve drawn on the basis 
of Horton’s theory about the distribution of erosion features in relation to 
the distance from the divide. One can remark that apparently the runoff in 
this landscape is dominantly of the type of the Horton overland flow. 
Apart from the distance from the divide another steepness of the land, 
the detailed slope fora in the point of observation has importance for the 
processes of erosion or sedimentation which take place (Young and Mutchler 1969 , 
Meijer & Wischmeier, 19^9)• In certain runoff conditions longej* slopes may show 
less erosion. (Haver, 1963 )• 
German investigations of soil erosion on hill slopes pay great 
attention to slope form. The development of erosion and deposition forms can 
be weak because of interference with the regular flow of rainwater runoff by 
terraces, field boundaries, roads and rock outcrops (Richter 1965 , Huron-et al. 
1956$ Hassenpflug, Richter 1972). 
EXAMPLE OF A SOIL EROSION TOPOSEQUENCE ON THE NORTH SLOPE 
OF THE GOTO AL TO, NAVAHOMBELA, SALAMANCA, SPAIN ^(figure 2 ) 
A detailed photo-interpretation of the erosion features in the arable 
land on the hills with a flat summit in the area, reveals a certain pattern 
in the features which correlate with the relief. On the contrary in the dis 
sected land on schist with more irregular topography, with many field boundaries 
at different intervals, and with irregular rockiness, there is no regular 
pattern of erosion features. 
The pattern of the erosion features on the hills with a flat summit can 
be found not only directly South of the village of Navahombela, but on all 
hills in the area which have a similar shape. As an example, a field descrip 
tion of the North slope of the Coto Alto follows here: 
The narrow flat summit has an inclination of 0-3% to the West. The relief 
is very gently convex. Splash erosion is dominant. Fine material is washed out 
and deposited in the ploughfurrows, while on the ploughridges relatively coarse 
material is left behind. The general soil texture is Sand to Loamy Sand. This 
layer is 0 f 5 - 1 meter deep. 
Over a short distance of about 10 meter the summit grades into the slope, 
which has an inclination of 5 - 8%. The substratum is a mixture of stones and 
' For a detailed description and some other erosion toposequences see Bergsma 1974»