at 
y 
y 
er 
  
  
  
  
| 
Wadi deposits 
q 
q 
A 
X 
VEE IE 
Fanglomerate 
Acidic volcanics 
Intermed. to basic volcanics 
Metasediments 
Metavolcanics 
Basic Metavolcanics 
  
Carbonates 
Oshib ultramafic complex 
Post-tectonic granites 
Syn/late-tectonic granites 
[Im 
ER 
BEE 
SS 
Faults and fractures 
; 
5 10 km 
  
  
  
Fig. 8: Geology of Wadi Amur area from visual interpretation of satellite data, aerial photography, and field studies; block size 
is 30 x 30 km?, corresponding to the area shown in figs. 4, 5, and 7. 
4 CONCLUSIONS 
A VAX-based geographic information system (ARC/INFO) 
together with a PC-based system (Atlas*GIS) is being used 
in the preparation of the geologic map of northeastern Sudan 
and for handling the considerable amount of data; a facility 
that was not available during the mapping project in Egypt. 
The use of Landsat TM data and of a GIS for geologic map- 
ping offers considerable advantages in many stages of the 
mapping process: 
© The superior information content of Landsat TM data in 
comparison to MSS is obvious. The interpretation becomes 
easier and the results are more reliable; the amount of 
expensive field work can be reduced. 
® Using a GIS, part of the visual interpretation can be per- 
formed directly on the screen. This makes the use of dif- 
ferent images for interpretation, like color-stretched and 
color ratio images, rather uncomplicated; the results of the 
interpretation of one data set can equally be used on the 
other set. In addition, any interpretation data from image 
overlays can be digitized and merged in the GIS data base. 
€ Storage and retrieval of all relevant data, from field mea- 
surements of structural features to petrographic and geo- 
chemical analyses, is greatly simplified. Essential informa- 
tion can thus be accessed and used during interpretation. 
331 
€ The resulting map can be corrected and upgraded as the 
work proceeds. Output of intermediate map products by 
the GIS at different scales (e.g. fig. 8) is uncomplicated, 
and "maps on demand" can be delivered at any time. 
® The various information levels held in the GIS can be used 
for classification by logic combination of different data 
sets. In this way, classification can take into account more 
than just spectral or textural data. 
® The final map can be produced quickly and economically 
by proceeding in a straight line from digital data created by 
the GIS to a raster plotter, directly obtaining screened 
plots for printing. No manual cartographic work is neces- 
sary for the time-consuming creation of the screened color 
printing plates. 
5 ACKNOWLEDGEMENTS 
The authors are indebted to Deutsche Forschungsgemein- 
schaft for funding the Special Research Project Sfb 69 within 
which the work in Sudan and part of the research in Egypt 
was done. Special thanks are due to Mr Coy. H. Squyres, 
former president of Conoco Egypt, who was the driving force 
behind the Mapping Project in Egypt, for his unwavering 
support and encouragement.