[meteorite-list] Mars Impact Bench - On Beyond Erosion
From: Jonathan Abel <abelcompany_at_meteoritecentral.com>
Date: Fri, 7 Oct 2011 11:09:05 -0700
Ron Baalke --
Your posts are among the reasons I enjoy this group so much! THANKS!!
I was immediately fascinated by your first image (link below) and mused
on the colossal forces that created a Mars impact crater 6 miles across.
And that bench -- hmmm...here's a layman's take...and I invite being
corrected by the group, whose passions and professions deal with these
On our way to Ruben's famous Holbrook Hunt we again stopped at Arizona's
amazing Meteor Crater and I recall driving up over a similar "bench".
Not as well developed or as obvious...and I know conditions, events and
timelines were very different on the two planets, but if you relate
Earth's best preserved and first proven meteor crater to the Mars
crater, I am nagged by the notion that the Mars bench was a by-product
of much more than erosion.
The explanation I was given at the crater for that "embryonic" bench on
Earth was that the heavier/more consolidated bedrock was lifted in what
I'll call "splash" forces and turned upside down. Thus the layered
strata was inverted...creating what must be an artifact of many impacts
- the oldest and harder crusty stuff is on top on the crater rim...and
our impact is geologically youthful - less that 50K years old, so solid
rock erosion can't be a big factor here...but do you agree we have the
makings of a bench?
Earth --- Meteor Crater Slide Show:
Mars --- Ron's Link - Crater with Surrounding Bench in Sinus Meridiani:
On Mars, the impact seems to have given rise to a similar geology as the
ancient hard-top sandstone pinnacles of Monument Valley -- good old
Earth-logical erosion would add to the severity of the Mars bench over
time...but only after a really good boost, eh?
What a sight that would be! To see the mixture of extreme forces at the
center of an impact act together to pry up the crust (possibly even set
some on edge); massive quakes and hot, explosive winds would maybe sift
by weight (like in a gold pan), melt solid rock (leaving an edge that
didn't melt) and there might even be a draining back into the crater of
melted or granulated stone (leaving a visible rim like high-tide at the
beach). And I'm probably missing other integral forces that would help
create a bench "on beyond erosion".
Received on Fri 07 Oct 2011 02:09:05 PM PDT