620 
Summarizing the results of this study, the following significant points may be 
listed: 
1. In areas where detailed or semi-detailed maps already exist, little new in 
formation can be expected from the analysis of ERTS-data. 
2. Limited resolution hampers both detection and identification of geological 
features. Future developments of the system should aim at an improved 
resolution. 
3. Mention was made of the capability of obtaining stereo-vision, which unfor 
tunately has not been fully exploited in the ERTS-1 system. The importance 
of stereo-vision cannot be overstressed in visual interpretation, and full 
stereo-coverage would have greatly increased the usefulness of the imagery. 
4. For mapping at scales smaller than 1:250, 000 ERTS-imagery can be used to 
the extent that it permits detection of major geological features, such as 
large lithostratigraphical units, and major structural trends. 
5. Considering the capabilities and the limitations of the system, the conclusion 
seems justified that ERTS-1 data can be used advantageously in areas where 
existing geological maps are of poor quality, in the reconnaissance stage,or 
absent altogether. Optimum results will be obtained in well exposed areas 
and in regions where favourable atmospheric conditions prevail. Under such 
circumstances ERTS images are considered to offer a useful source of infor 
mation for regional mapping at small scales. 
REFERENCES 
[l] MEKEL, J. F. M. , and 
VANDER MEER MOHR, H. E.C. 
Explanation of the photo-geological 
map of the Montalban region. ITC 
series B, No. 59, Delft, 1971. 
[2 ] RAKSHIT, A. M. , and 
BHATE, V.D. 
Evaluation of ERTS Imagery of Zara- 
gosa area, Spain, for geological map 
ping purposes. Unpublished report, 
ITC, Enschede, 1973. 
[3] SHARMA, R.P. , 
Application and Assessment of ERTS 
MSS Imagery of Montalban area, 
Spain, for detailed geological mapping. 
Unpublished report, ITC, Enschede, 
1973.