681 
4.3 Verification of the result 
ROCKS 
mechanical ero- 
climate. This 
37) as the con 
ig" (see figure 4). 
. of the sediment 
.tic condition, 
,s as much as 100 
■nts fringe the 
id by rejuvenation 
irginal pediments 
id wash plain. 
;e that the wash 
nger distance 
;per sedimentary 
)th estimation 
Pediment . 
e of deep weathering 
/ 
1 or rim pediments 
corresponding to the thickness of younger sedimentary 
rocks. Thus, the patlem of the basement rock dem- 
sity must be indicating the thickness or the relative 
depth to the basement of sedimentary rocks. 
123°E 124°E 
123°E 31°S 124°E 
(a) Original distibution 
rpothesis of 
lg processes. 
>f the study area, 
>d is used. The 
;ering method 
nr-channel Land- 
l homogeneous 
sixteen items by 
are interpreted 
? near the ground 
?y and aerial 
■tiled "Basement 
it rock were 
n. The maximum 
}. The original 
i. The result 
1 the trend of 
?chnique was em- 
ciginal data was 
sement rock pixels 
smoothing window 
n x 7Km, and 9 Km 
im x 9 Km was the 
5.b). 
123°E 
124°E 
30°S' 
(b) Smoothed distribution (window 9x9 Su) 
frequency 
sity must be 
Figure 5 Basement rock distrbution map 
It is necessary to compare the real depth with the 
other data such as boring test. However, it is not 
possible to receive real depth in such vast area. 
Thus, we compared it the gravity map. Depth estima 
tion map in figure 6 is analysed by double fourier 
series with two harmonics in both directions to get 
the effective trend surface. 
There is more or less the same trend of relative 
depth in both method, Landsat data analysis and an 
airbone gravity. According to such verification, 
this method and the result can be trustworthy for the 
pourpose. 
a 
iso-gravity line 
Landsat MSS 1 -90A-Z-+ 
(D) « *(S) 
deep shallow 
Figure 6. Comparison of estimated depth between 
by Landsat MSS and by airbone gravity survey 
5 PALEO CHANNEL DETECTION 
5.1 Relationship of paleo channel and present topogra 
phy 
Paleo channel mean the old river which had been cover 
ed by the new sediments. When there was the river 
channel the climatic condition was more rainy than 
present time. The river transported more and coaser 
sand/gravels. Climatic condition was gradually changed 
to dry and hot. Thus, total amount of sediments was 
relatively small. And also there was not influenced 
so much by the crustal movement in the recent term. 
The river channel could be remained its characteristics 
as the paleo channel under those two geological envi 
ronment . 
The paleo channel is composed of coaser materials 
and it makes permeable zone for the ground water. 
By means of aerial photo interpretation and field 
observation, the relations between topography, geology 
and vegetation which is summarized on the figure 7. 
The highly undulated area is sand dune, where have 
barren vegetation. And depressional area have flat 
bottom, where is covered by dense vegetation with 
short trees and grass. There is composed of fine 
materials on the top and located over the shallow