IAPRS & SIS, Vol.34, Part 7, “Resource and Environmental Monitoring”, Hyderabad, India, 2002 
  
1.5.4 Crystalline Block: There are two prominent 
directions of lineaments trending N45°E-S45°W and N75°E- 
S75°W. There are 70 lineaments in the NE sector, followed 
by 48 in EW, 40 in NW, and 29 in NS sector with a total of 
187 lineaments. By measuring the lengths of the lineaments 
it has been observed that 63% of the total of lineaments 
extend upto 2 km, 35% have length between 2-4 km and 
only 2% are greater than 4 km in length (Table 4). 
Table 4 . Direction and lengthwise occurrence of number of lineaments in Crystalline block. 
NE-SW NW-SE N-S E-W 
2 km. 38 32 20 28 
2-4 km. : 30 8 9 18 
>4 km. 2 0 0 2 
Total 70 40 29 48 
  
  
  
  
  
  
Figure la. (Upper) Rose diagram showing directional 
distribution of lineaments in the study area. 
Figure 1b. (Lower) Schematic diagram showing 
directional distribution of tectonic forces 
and orientation of major and minor lineaments 
developed due to these forces during different 
: phases of deformation. 
  
1.6 RESULTS AND DISCUSSION 
The lineament pattern clearly depicts that in the entire 
region several lineaments occur parallel to each other. This 
implies that the stresses, which produced these features, did 
not act locally but over a large region. Due to these stresses, 
a number of weak zones are developed in a particular 
direction in the various litho-tectonic blocks. 
The lineament distribution in the study area indicates four 
prominent trends. These are N55°E-S55°W, N50°W-S50°E, 
N90°E-S90°W and N10°E-S10°W (Fig la). The rocks of 
Tehri-Uttarkashi area experienced four phases of 
deformation during the Himalayan orogeny (Saklani 1993). 
The various structural features viz., axial plane foliation, 
484 
three to four sets of tectonic joints (strike joints, dip joints 
and oblique joints), fractures, faults and folds were 
developed due to these episodes of regional deformation and 
tectonics. During the development of E-W trending major 
lineaments (e.g., Uttarkashi fault) the maximum Principal 
compressive stress (O 1A) was directed from N-S and the 
least Principal compressive stress (03A) acted along E-W 
direction. The intermediate Principal compressive stress 
(02A) was vertically directed (Fig 1b). The minor 
lineaments were developed around N30°W- S30°E and 
N30°E-S30°W. The major lineaments can be correlated with 
E-W plunging folds (Phase I) of Saklani [(1971,b) in 
Garhwal] and Naha and Ray [(1970 in Simla]. 
The NW-SE trending major lineaments along N50°W-S50°E 
together with minor lineaments along N20°E- S20°W and 
N80°E-S80°W were developed due to stress transfer from