COMPARISON OF DISSECTION PATTERNS OF MARS AND EARTH DERIVED FROM DEM

Comparison of global scale drainage dissection patterns of both Earth and Mars offers some new insights into the past climate for Mars. The dissection patterns were extracted from digital elevation models (DEMs) of the two planets using a morphology-based algorithm, which is capable of revealing spatial variations in dissection. The drainage density for Earth consistently increases with elevation, reflecting Orographic effect of rainfall, whereas that for Mars shows a fluctuating but more or less constant trend at lower elevations and a general decreasing trend at higher elevations. The terrestrial drainage density increases with local slope, reflecting the dominant role of erosion from rainfall runoff, whereas the Martian counterpart only increases with slope at moderately high slopes. These trends are more consistent with a Martian paleoclimate that only supported episodic and short-lived precipitation events. In addition, the terrestrial valley depths show no clear trend with latitude, but those of Martian counterparts generally decrease with latitudes, which may reflect the effect of strong terrain softening at higher latitudes on Mars.>