1. Drainage basins and Channel incision on Mars Aharonson, Zuber, Rothman, Schorghofer, Whipple Robert I. Davies San Francisco State University

4. Channels on Mars Material squished out by impact

5. What are the evidences of Free water on Mars? Was there a climate on Mars that supported rainfall? How are channels formed? What is the hydrology of Mars?

6. Channel Incision Results from Surface Runoff Groundwater sapping –Erosion along the base of a cliff, and allowing the rocks above to fall in large blocks –Erosion around a spring at the headwaters of a spring –Undercutting along the headwall of a cirque, owing to frost action at the bottom of the bergschrund

7. Terrestrial Analog East & West arms of the Escalante River –East- Channel incision progressed via headward erosion aided by seepage of groundwater at its base –West - Tributaries evolved primarily by runoff

8. Comparison of Stream Profiles Al-Qahria Vallis Ma’adim Vallis Browns Canyon The geometry of the profile is characteristic of groundwater sapping, rather than overland flow.

9. Calculations Comparison of Stream gradients on Earth and Mars, given that S  A -   =.02 for Mars  =.07 for Earth

10. Graph comparing concavity of streams on Earth and Mars

11. Conclusions Slope-area relations show no evidence for fluvial sculpting Topographic measurements suggest that sapping is the primary method of channel incision

12. Question #6 What role does gravity play in all this? Mars’ gravitational acceleration is only 3.745 m/s/s