On Mon, 19 Sep 2005 21:33:00 -0500, "Martin H. Eastburn"
wrote:
Martin Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
NRA LOH, NRA Life
NRA Second Amendment Task Force Charter Founder
Cliff wrote:
On Sun, 18 Sep 2005 22:07:44 -0500, "Martin H. Eastburn"
wrote:
I would guess it is 2,000 feet myself.
Source clearly stated 20,000 feet. I was a bit startled myself.
No source given - perhaps they are talking about Basalt.
They said sandstone.
Documentary on the construction of the Lake Pontchartrain Causeway,
but I *may* have heard it wrong too ....
I can't find my Gulf States Stratigraphic
class book with the secret notes within. (Secret because oil, gas and water drillers
would kill for some of it at the time).
They drill past it.
No they drive past it or drill short in x or y dimension - they would spot traces in the water
if through it.
??
This was mentioned as being that sandstone. IF we have the same
subject.
You don't have to be in sand stone to have rock.
True. But that's what seems to have formed there. It is,
after all, geologically new and produced from sediments.
Wrong - only the surface is the latest stuff.
Not "latest". "Geologically new".
As you go down it gets older and older.
Naturally when an uplift occurs - Cen Tex - the old old stuff hits the surface and the
stuff under is old and oldest.
That's not an uplift. That's an inversion or something IIRC. There's
a specific name for it .... which I cannot recall at the moment.
Folding can leave the older stuff atop the newer.
Never studied much, if any, geology. Wish I had at times.
Limestone is hard rock deep under.
Only where it was formed.
No it isn't limestone - travertine or that stuff in a glass.
??
Travertine becomes limestone too IIRC. And limestonecan precipitate
in high CO2 environments IIRC.
It hasn't
It turns into rock by compression and heat.
I don't recall much of either being needed.
Coral reefs are friable - I step
here or there and get cut but crunch this or that. Some Brain corals form central
'rocks' but this whole mass is compressed by the next 100' of coral on top.....
In the Rockies - there are massive coral reefs - high in the mountains. From folding
and because the mountain rose.
I want to say it is at 400' deep in Houston and San Antonio - so it would be much
the same in the delta. I did once know the strata layers from the gulf to the panhandle
and likewise up from the coast in Mississippi....
The delta is over what was once the continental shelf, if not
beyond.
No - not really.
Per the map (cited below) too.
The gulf was blasted out by one of the world class objects from space.
??
You are not confusing this with the Alverez event in the Yucatan,
are you?
It is forming a massive shelf - all the way past the islands of the Gulf area - north of
South America. The central area is being filled in slowly - Much of North America
poured out the rivers as the Ice retreated and the oceans retreated back.
And how deep a canyon was scoured under the site of New Orleans?
Topological maps of the seabed show many deep ones world wide,
all old IIRC.
The oceans
retreated because of the Continental Arch - and the New Mex. Texas Arch.
LA - and parts of north east Texas, through the Red River area - are in the Arbuckle Basin.
BTW, Why do continents have shelves?
A shelf begins after a content drifts from a spreading crack. The area is slowly filled as
it spreads (toward the filling region if on the East coast as an example.) The constant
flow off the continent dumps junk over the edge and fills in the edge. It continues and pushes
out wider and wider - the soft junk mushes out and down and re-fills.
I am rather certain that continental shelves are not made of
deposited sediment.
It was inland oceans time and time again.
Retreating and depositing.
Probably not there.
YES there.
Kind of hard to have an "inland ocean" on the coast.
For certain there as they retreated from Montana and their last beach is the
current beach of the Texas and La... gulf. Perhaps and that is perhaps the ocean will
retreat more - as it has or comes back and takes back the 'beach' area - the first 50 miles
or more - In Geologic time - that region is a flick of a cat tail.
A trench 20,000 deep filled in with muck from the Mississippi would be strange indeed.
Nothing that tall or that deep ever was in North America or on the Plate. IBY
[
The Sigsbee Deep, located in the southwestern quadrant, is the deepest
region of the Gulf of Mexico. Its exact maximum depth is
controversial, and reports by different authors state maximum depths
ranging from 3,750 m to 4,384 m. Mean (average) water depth of the
Gulf is ~1,615 m
]
The map at http://www.gulfbase.org/facts.php shows
Nice Map!
The baby blue is the shelf - the new junk over the edge stuff -
The blue is the deep hole filled in. The area was either blown out or was
split out of other continents - but it is believed it was a killing zone.
"Little is known about the geologic history of the Gulf of Mexico
Basin before Late Triassic time."
"The present Gulf of Mexico basin, in any case, is believed to have
had its origin in Late Triassic time as the result of rifting within
the North American Plate at the time it began to crack and drift away
from the African and South American plates"
No big boom ..... and where would the ejecta be off to?
And it would have been a much larger boom than the Alverez
Yucatan event ..... which ended much life on the planet. The Gulf
is too young for such an impact to have exterminated life a
billion or so years ago.
the entire delta as being on the continental shelf though.
The delta makes the contentental shelf.
Nope.
BTW, When plates collide & one is subducted ..... why
are not the top layers of the subducted one scraped off
to build up mountains at the subduction zone?
There should be mountains off the Pacific coast ......
I'd guess that they made a "typo" on that 20,000 feet -
might be 2,000. (I copied it down at the time G.)
http://www.southbear.com/New_Orleans/Geography.html
[
Lake Pontchartrain and Lake Maurepas were created about 5000 years ago
]
And the last ice age ended when?
--
Cliff