International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B4. Istanbul 2004
N
Rose diagram 19
NW. NE
We Y3
SW: SE
Aspect
pointing downslope
Figure 9. Rose-diagram of Valles
Marineris.
Figure 8. The computed gradient for the study area (top image). Aspect
(bottom image) standardized to the 8 directions defined in a raster image
(Figure 7), the black was used for flat terrain (if gradient « 2 aspect is
considered undefined).
e Aspect rose diagrams are completely different (Figures 7
Aspect Number ou and 9) although the main axis of both features is parallel to
Direction | of pixels Statistics the East to West direction. More specifically, the Grand
Canyon terrain is developed mainly in a East to West
E 126,468 = Mean 1468.9 direction that is parallel to the fluvial processes main
NE 105,115 9 St.dev 384.7 direction while the residual tributary canyons occur in a
N 96,206 S E | Maximum 2,703 North to South direction.
NW 119,602 = Minimum 294
W 136,523 HI 0.49 Aspect J Sumber statistics
SW 110.128 Y TET Direction | of pixels
1 L i 2an .
ë te E 45.000 Mean 474
S 92050 |] 5 St.dev 14.60 : g :
8-3 : NE 79,469 1.2 St.dev 3,086
SE 112,594 | s — Maximum Sn ;
o - N 101,416 | 9 £ | Maximum 6,925
Flat < 2 147.252 [OC Minimum 75 o _
NW 45,356 | om Minimum -5,749
W 38,213 HI 0.41
Table 1. Geomorphometric signature of Grand Canyon SW 74,479 n Mean 9.89
S 100,076 | © _ | St.dev 9.0
The overall comparison of the two features (Grand Canyon S € e IT
: eri heic nf : : I SE 51,093 & —| Maximum 53
versus Valles Marineris) on the basis of the corresponding = es 5
geomorphometric attributes (Tables | and 2) indicates the Flat « 2 139622 Minimum 0
following:
e. Grand Canyon is more massive since the HI (hypsometric
integral) is greater.
e Grand Canyon is much more steep than
e Valles Marineris chasma that presents greater variability of
relief with respect to both the standard deviation of
elevation and the local relief (elevation difference)
Table 2. Geomorphometric signature of Valles Marineris
On the contrary in Valles Marineris chasma the landscape is
developed mainly in a North to South direction that is vertical
to the huge elongated mountain ranges that are evident with the
chasma. This means that the landscape flow away from the
e Valles Marineris presents remarkable straightness of
: ; i mountain fronts and not parallel to a supposed fluvial processes
mountain fronts in comparison to Grand Canyon.
along the West to East direction. In other words the process
responsible for the shape of the rectilinear mountain fronts
