Morphology   unit          
Altitude   (m)           
Average   gradient          
(Degree)           
Formation of   protrusions           
considerations           
Mountain          
1800          
30 - 50          
Karaj Formation   (tuff, …)          
It seen in the mountains north of Tehran          
Hill          
1500          
20 - 30 (hill)          
30 - 40 (foot)          
A & B Formation          
Height of Saadat Abad,   Tarasht & Abas abad.          
Old          
Fan          
1000 - 1500          
5 - 10          
C Formation          
Plain of Evin,   Tajrish, Niavaran, …          
Young          
Fan          
1100 - 1400          
less than5          
D Formation   (Coarse-grained)          
Stream, old and   new river routes          
Plain          
1000 - 1100          
Smooth          
D Formation   (Fine-grained)          
South of Tehran