[BR-Crater] ready to update SEIS entry?

[Ian Kluft]

On Thu, Feb 12, 2009 at 06:09:43PM -0800, I wrote:
> [...] Since it's difficult to see the terrain 
> features on the map scale that it takes to see the whole diameter of the 
> structure, I'd like to hear from a few people who have verified it before 
> I send an update to IFSG. [...]

I heard from Rich Loring, the retired geologist from Reno who recently
joined the mail list.

He cautions against just using only topographic features to recognize the
newly-proposed crater outline.  Taken alone, they can be misleading.

I agree - for example, we started this before Google Maps had the terrain
(relief map) feature.  The inconsistently stitched-together satellite
and aeral photos often lead to what I call "Googillusions" as people think
they can see circular features everywhere if they want to - including by
positive and negative relief and artificial features.  It was mostly
unusable for our purposes.

Rich started with a look at the topo maps.  That led him to go check the
Washoe County geological maps.  So far both the topo and geological maps he
has looked at are 1:250,000 scale.

He's cautious like any scientist should be.  He said that on the geologic
maps at have some features that may match the observed circular outline
better than on the topo maps.  There are sediments and volcanics on the
maps which could be indicative of crater infill.  He emphasized "could"
because it's all preliminary observations of those maps, which will need
further work.  It sounds like he has ideas for further field exploration
in addition the one I've already suggested (Pahsupp Mtn) for the next
trip.  That sounds good to me.

We made similar observations about the Soldier Meadows Tuff.  Any of these
pieces of the puzzle don't necessarily say much alone.  But we collect them
all to see if the big picture points toward or away from the hypothesis, or
suggests changes to it.

I'll make arrangements to meet Rich in Reno to hear more about this.  I'm
sure there will be observations to record on the crater research web page.
For now snowy weather is likely to interfere with non-urgent travel plans
over the Sierras for the next week.  There may be breaks between storms.

As for when to send an update to IFSG with the 87 km diamater and new
coordinates for the SEIS entry, it can wait a little while since it's under
discussion.  However, we also should remember that we have the option to
send updates on a recurring basis.  So we don't want to set the bar too high.
Currently the entry is listed with a confidence level of "possible" which is
where most entries start on the list.  The entry currently has the old 30x40
mile ellipse and old coordinates based on topographic observations - so it
only needs to be better for an update.  We certainly don't need to wait
until we have enough info to write a conclusive paper for a journal before
we send them an update.