Published online two days ago in JGR-Planets:

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Coleman, Neil M.
Aqueous flows carved the outflow channels on Mars
J. Geophys. Res. Vol. 108 No. E5
10.1029/2002JE001940
15 May 2003

Abstract

The role of water in carving the Martian outflow channels has
recently been challenged by the hypothesis known as "White Mars."
This hypothesis claims that the channels were cut by CO2 gas-
supported debris flows that also resurfaced the northern plains.
However, proposed analogs of "cryoclastic" flows are either
inappropriate (i.e., submarine density flows) or are primarily
depositional rather than erosional (i.e., pyroclastic flows).
Subaerial mass movements on Earth do not carve long deep channels
like those on Mars. I review runout efficiencies for mass movements
on Earth and Mars. The efficiencies required for "cryoclastic" flows
to resurface the northern plains of Mars are so large that they
appear unattainable. White Mars seeks to resolve carbonate and
floodwater "paradoxes" that probably do not exist. It is also
doubtful whether reservoirs of CO2 could persist over geologic time
in the crust. Overall, the CO2 hypothesis fails key tests and should
be abandoned as a means to carve outflow channels. I present a new
interpretation of the fluid source that created Aromatum Chaos and
Ravi Vallis. Water, not liquid or gaseous CO2, was the causative
fluid, and the source was an ice-covered impoundment in ancestral
Ganges Chasma. At that time the canyon had no eastern outlet, and
groundwater flowed northward to discharge at Aromatum Chaos and
Shalbatana Vallis. The presence of ice-covered water bodies can help
to calibrate models of volcanic-hydrologic climaxes during Hesperian
time. The outflow channels, like the spectacular landforms of the
Channeled Scabland, are monuments to the erosive power of
catastrophic aqueous floods.

Received 19 May 2002; revised 6 October 2002; accepted 3 January
2003; published 15 May 2003.

Keywords: White Mars, outflow channels, Ravi Vallis, Ganges Chasma,
groundwater, carbon dioxide.

Index Terms: 6225 Planetology: Solar System Objects: Mars; 5415
Planetology: Solid Surface Planets: Erosion and weathering; 5470
Planetology: Solid Surface Planets: Surface materials and properties.

Citation: Coleman, N. M., Aqueous flows carved the outflow channels on Mars,
J. Geophys. Res., 108(E5), 5039, doi:10.1029/2002JE001940, 2003.