Table 1 
Air photo interpretation and verification of soils around Ambala (Haryana) India 
e construction 
; much, or after 
layers of the 
reconnaisance 
I to be 
ty of soil as 
Information 
n be had 
ehnique, even 
ial plains 
of about 650 
in the 
of India had 
ographs, for 
pes. Some of 
A INDIA 
>N TECHNIQUE) 
Site Location 
SL. 
Soil identification 
by Airphoto Inter 
pretation 
Unified Soil 
Classification 
as per lab. 
testing 
Remarks 
1. Jathsar Village 
Silty Clay (CL) 
CL 
2. Luthar Majra Village 
Silty Sand (SM) 
CL 
Kalar area (Sulphate 
infested) 
3. River bed opp. to 
Arjana Kaund 
Sand (SP) 
SP 
4. Umla Naia Trough 
Silty Sand (SM) 
5. Near R. D. 200 right 
side of Canal 
(Jhensa to Jansol) 
Clayey Silt (ML) 
SM 
CL-ML 
6. Thaskali Village 
Clayey Sand (SC) 
SC 
7. Adopur Village 
Silty Sand (SM) 
SM 
• ROAD 
- RLY LINE 
VILLAGE & TOWN 
RIVER 
s andy 
8. Khwaspur Village Pond 
9. 8/7 right side 
Ambala Chandigarh 
Road 
10. Ghagar River bed 
11. Ghhajnu Village 
12. Near R.D.205 Umla 
Clay (CH) 
Silty Clay (CL) 
Sand (SP) 
Clayey Sand(SC) 
Clayey Silt (ML) 
CH 
CL 
SP 
SC 
CL-ML 
the soil thus delineated were silty clay (CL), 
silty sand (SM), sand (SP), clayey silt (ML), 
clayey sand (SC) and clay (CH). A part of the soil 
map thus produced and a stereo pair are given in 
Fig. 1 and 2 respectively. On ground verification, 
it has been revealed that it has been possible to 
interpret engineering properties of soil from the 
aerial photographs. The correlation of some of the 
interpreted sites is given in Table 1. 
3.2 Delineation of soil boundaries in the sandy 
terrain of Nigeria 
ous horizon under an overburden of 0.5 -2m of soil 
as shown in Fig. 5. They are of different shapes, 
forms and sizes. They may be granular or in the 
form of clod. The colour is usually light grey. 
A typical hard variety of calcrete is shown in 
Fig. 6. 
The deposits of calcrete in tropical countries are 
said to be formed by the process of calcification. 
Carbonated rain water dissolves calcium carbonate 
(CaCo3) present in the local soil, converting it to 
soils in part 
Similarly, soils accuring in the sandy terrain of 
North-East Nigeria (part of Bomo and Kano States) 
covering an area of about 18000 km^ have also been 
interpreted from the aerial photographs and classi 
fied according to Unified Soil Classification 
System. Predominantly the soils identified are 
silty sand (SM) clayey sand (SC). Their photo tones 
var^ from light grey to dark grey and sometimes with 
whitish tinge due to the occurence of sulphate and 
calcareous deposit. The other soil types identified 
and met with in certain areas are sandy silt (ML), 
clayey silt (MH), silty clay (CL) and clay (CH). 
A stereo pair and a typical map are given in 
fig. 3 and 4 respectively. 4 
4. SURVEY OF CALCRETE 
Calcrete is an English term used for calcareous 
aggregates commonly met with in the alluvial plains 
and desert terrain of India and under aeolin deposits 
in North-East Nigeria. Locally these aggregates are 
called 'Kankar' in India and Jiglin in Northern 
Nigeria. Generally they are not visible at the 
surface and occur at shallow depth as a semi contin- 
Fig. 3 
Stereopair showing silty clay (CL) in part of 
North East Nigeria.