the ERTS-1 MSS imagery in conducting soil surveys. Even in the cases where 
the plant coverage is the dominant factor, the knowledge of the soil-plant relation 
ship could give good hints about the soil situation. The above holds true for both 
MSS imagery as taken by the ERTS -1 satellite and conventional aerial photography. 
The added dimension with the ERTS -1 MSS is the production of four different 
images for the same area. A number of methods were tried to take advantage of 
this fact and efforts made to compensate for the poor resolution and lack of 
stereoscopy. Some of the preliminary results will be given below. 
Various landforms on different bands of ERTS-imagery 
Of the four different images produced by different MSS bands, band 4 was the 
least useful. It was generally too dark and it seems likely that the atmospheric 
scattering plays a more important part at these frequencies. Almost all the land- 
form units were seen better in the other bands. The one exception was some areas 
with a very sandy surface, probably of aeolian origin. These areas could be clear 
ly distinguished on band 4. 
The images of bands 5,6, and 7 were more useful. Band 5 seemed to be more in 
fluenced by the colour of the surface stones and bands 6 and 7 by the moisture 
conditions and plant coverage. Human constructions such as roads, towns, etc. 
were clearer in band 5, and water bodies in bands 6 and 7. 
The resolution on all three bands, 5, 6 , 7 was similar and within the limit of 
100 m as predicted before the launch of the satellite. In one case a road and a 
railroad could be easily distinguished, although the total width of each of them 
as measured in the field was not more than 15 m, including drainage ways and a 
grassy strip alongside. This, however, was an exceptional case of a road running 
perpendicular to the scanning direction through an area of dark soils. In general 
roads are not so clear as most of them are narrower than the limit of resolution. 
A comparison between the appearances of different land types inside the valley of 
Guadiana River corresponds with certain soil associations, shown on bands 5 and 
6 ,are given below. The facility of drawing an interpretation line is indicated as 
mappability. The remarks on band 6 are also valid for band 7. 
ALLUVIAL VALLEY OF GUADIANA 
Recent deposits 
Appearance: Band 5 moderate grey toned matrix with appearances of former 
channels in darker lines. 
Band 6 : moderate grey tone. Former channels not visible, unless they hold some 
water. In this case they are clearer in band 5. 
Mappability: moderate in band 5, worse in band 6 .