More on Olympus Mons

From: (Ken Edgett)
Subject: More on Olympus Mons
Date: Fri, 23 May 1997 09:02:01 -0700 (MST)

Dear Mars Educators-

I had another thought last night regardin the Olympus Mons
elevation story....

The article in July '97 ASTRONOMY said that Ascraeus Mons was now
considered to be taller than Olympus Mons.  

I would agree that it's quite likely that the summit of Ascraeus could
be slightly higher than that of Olympus Mons.  Based on how we recon
heights on Earth, that would make Ascraeus the tallest mountain on 

... However, Olympus is *actually* the taller volcano. Ascraeus could
very well have a summit elevation that is higher, but if you look on
a topographic map of Mars, you find that the BASE of Ascraeus Mons
is at a higher elevation thant the base of Olympus Mons.

   In the 1991 US Geological Survey topographic maps, Olympus Mons'
base is at about 4 km elevation, but Ascraeus' base is at about 9 km
elevation...  Olympus Mons would still be the TALLEST.

   In terms of areal extent, there has been some arguement as to
which is the biggest-- and I think either Arsia Mons or Alba Patera
beat out Olympus on this one  (note that Alba is very flat, but very
large in diameter.  Also note that if you count the flows coming
out of the southern flank of Arsia Mons, then Arsia is probably 
the biggest in terms of area covered).

Ken Edgett
Arizona Mars K-12

p.s. I still have doubts about the Margaritifer Sinus low elevation,
but I am intrigued, nonetheless--- it might help explain some of the 
features there...