QUESTION: 
The Pathfinder site is either  a washed-out area or a  built-up area
which  would  be  sedimentary.    Based  on  the  appearance  of the
tear-drop islands nearby it appears  to me to be wash-out,  or lower
in elevation than the preflood  surface.  Which is correct  and what
specific data supports your answer?

ANSWER from Mary Urquhart on August 27, 1997:
The  catastrophic  flood  did  carve  a  channel  as  evidenced by the
existance of Ares Vallis, teardropped islands, streamlined hills,  and
apparent groves in part of the floor of Ares Vallis which are probably
erosional in origin.  As  the flow expanded into Chyrse  Planitia some
mottled terrains  are present  which suggest  that the  upper layer of
rock may  have stripped  away in  places by  the flood.   Sediment was
transported into  the Chryse  region, and  probably included  boulders
(some estimates  say up  to 10  m or  about 30  ft across)  as well as
fine-grained  material.    Pathfinder  landed  near  the mouth of Ares
Vallis in Chyrse Planitia.

The actual landing site of Pathfinder may have been both carved out by
the flood waters and the site of deposition of sediment.  One possible
scenerio is that the flood initally carved out some of the rock in the
area (such as the sides of the twin peaks) and then later boulders and
the undulating sediments were deposited  in the area.  The  variety of
rocks at  the Pathfinder  landing site  is strong  evidence that flood
deposition  did  occur  in  that  area  (as  was predicted by the site
selection team).   Whether  or not  the landing  site experienced more
erosion than deposition isn't really known at this point.

Mary Urquhart
Laboratory for Atmospheric and Space Physics
University of Colorado at Boulder