Impact Craters
 

I have always been fascinated by impact craters. Also by history. When I was snooping around for references to the era when the Greeks dominated Mediterranean culture, I ran across this map:

http://www.lib.utexas.edu/maps/europe/greece_pol96.jpg
(Large image)


The shape of the Aegean Sea surrounding the Cyclades Islands off the coast of Greece was very intriguing. I went search for images of the area and found this one. It's on a very nicely done personal travel site named Milos Is For Lovers, but it's a satellite photo.

http://homepage.mac.com/andreasfmpro...ce_map1024.jpg
(Another large image.)


If I'm seeing what I think I'm seeing, it would appear that the Cyclades are the peaks of a central cone in a very large impact crater that made the Aegean Sea. The crater rim looks like to goes around Crete, Karpathos, Rhodes, through Turkey, across the Dardenelles, and back around down the spine of Greece. Now I'm wondering if maybe the Sea of Marmara and maybe even the Black Sea were formed in the same event, perhaps by other impactors accompanying the one that made the Aegean. :thinking:

The very rugged terrain around Gallipoli that caused so much trouble to allied troops in the Battle of Gallipoli (wikipedia link) in WWI would be fairly consistent with that theory. But then being at the place were continents collide the terrain would be rugged anyway.

Yeah. The import feature to look for is the distinctive topography of a crater rim. Craters are always circular with a raised rim and sometimes a central peak. Those mountains around Gallipoli definitely look like part of a huge crater rim that goes all the way around to the spine of Greece.

And it was the mountains in Greece that defined the Greek culture. The rugged terrain there was what made them a seafaring culture. Perhaps it was all due to some big impact that happened three billion years before.

I've always thought just the same thing about Wilpena Pound, in the Flinders Ranges of SA.

From above, it is a great big bowl, with jagged cliff peaks all around the pound.

From that description, Wilpena Pound definitely sounds like an impact crater.

This is from the Australian Museum Geoscience page.


Wilpena Pound is a huge natural amphitheatre in the southern Flinders Ranges of South Australia, 400 km north of Adelaide. It is a large basin-shaped structure ringed by cliffs, made up mainly of the Pre-Cambrian age Rawnsley Quartzite. It covers an area of 83 km2, and the interior measures 11 km by 8 km. Although it has a crater-like appearance, it is not a meteorite impact crater. The Rawnsley Quartzite (in the Pound Subgroup) is made up of quartz-rich sediments originally laid down in a large ocean. The structure was originally a huge dome pushed up by earth movements about 650 million years ago. The floor of the Pound is about 200 m above the surrounding plains, and the outer ring of cliffs rising 500 m from the plains is all that remains of much higher mountains surrounding the Pound, since eroded by many thousands of metres. The highest prominence is St. Marys Peak, at 1170 m above sea level.

Australian Museum Online
Copyright.


Apparently not an impact crater. No matter.

Aw darn. That's one that got away. Perhaps it's a sinkhole.

Nope.:laugh:

The "Pound" is part of the Flinders Ranges. Geologists say the range is the remains of a mountain range that once stood higher than the Himalaya's.
But, we do have impact craters abounding. I'll chase a bit up for you later.

Pension day today. Today I give other people money so I can live, eat, etc.
Just like real people.:p :laugh:

Now you've got me curious about how high the Appalachians were when they were young and proud...

Pretty tall I reckon, but, they are only youngun's.
Dear old Oz, is the oldest landmass on the planet.

PS. I still haven't got off the farm yet. Went to shower, turned the tap (fawcett) no bloody water. Do the tour of 3 miles of waterline across the paddocks. Found 4 leaks. Bloody Hell.
Fixed now. Now, maybe, I can get spruced up, in the "sunday go to meeting clothes", and go pay some bills.:help1:

Lol, looked 'em up on Wikipedia. 480 million years old, originally created during the formation of Pangaea. Eroded flat, uplifted again!

I'm actually in the "Allegheny Plateau" in southwest NY.

Yep, just puppies. Change the "m" to a "B" for billions of years, that's Aussie. Old, and a bit harsh at times, but beautiful.

Aussie can't be more than 4.5 billion years old. That's how old the whole planet is! The bare rock from that era is also visible up around Hudson Bay; the glaciers have just bulldozed down to it.

:laugh: The whole universe is only about 20 billion years old!

Maybe not lots of billions of years. Pretty damned old though.
Some of the oldest surface rocks on earth.
"Mungo man" remains predate most other human fossils found.
Cycad palms still living from the time of the dinosaurs.
"Wolami Pine", that was thought to be fossil only specimens, until a couple of years ago.

I'm a little hazy on the actual time frame of course, but it is something to do with when Gondwanaland split off from Antarctica.
I was pretty young at the time, so I don't recall it all that well.

Edit.

And now to get back on track we have this link.
http://www.angelfire.com/stars2/messier/Impact.html

The Wolf crater is very impressive.

:laugh: Yeah, not even my memory goes back that far!

Nifty impact craters! Those pix are also a nice view of what the terrain looks like. It doesn't look like the kind of place where a lot of people would be too terribly upset if I were to make a mess of it.

You mean something like making another crater inside it?

Not really. Be a change, to have something to talk about.

Picture the Sahara, colour it red.
Picture the Gobi, put a pile or two of really big rocks around.
Picture Death Valley, but LOTS bigger.
And every where there is Spinifex bush.

What is Spinifex? It bites. An innocent looking round needle leaved desert plant. Grows about knee high. Don't try to walk through it. It will eat you off at the knees.:laugh:

And the Goanna's. When frightened, they climb to the top of the highest thing they can see.
Um, that's you Tex, I'm only 5 ft 6 inches.
Goanna's have very good claws, for climbing when frightened.
What frightens Goanna's? Tall things.:laugh:

Ooh, ooh. Look. I use this as my Winslows desktop.
It's pretty typical of the inland.

Neat! It's kinda pretty in that picture, although not a place I'm hankerin' to visit any time soon.

I'm sure there are a few people would object to running a strip through the pristine desert wilderness, threatening the habitat of rare spotted spinifex and blocking the migration of the even more rare paisley goanna, but what the heck. I'm only talking about a blight on the landscape about the width of the right of way of a four-lane superhighway, sort of, mostly, more or less.
Erm... quite a bit more down toward the Alice Springs end.

Well, that the environmental impact statement, which is likely to include providing irrigation water for a few odd square miles of the desert at the risk of maybe tripling the amount of arable land on the continent. I can see as to how that would be a horrible thing.

It is truly beautiful out there mate. I intend to do a 4WD trip, 3 to 4 months time.
Only a few days, after the rains this year, the wildflower show will be spectacular.
After a rain the deserts turn from red dust to the most vibrant and riotously colourfull place I've ever seen.

And personally, I don't see how an "interplanetary superhighway" can do any more damage than we already have.

Hell, the British blew half the southern end of the deserts away with A bomb tests during the 1950's. And the Monte Bello Islands off the North West Cape copped that treatment as well. What the hell else can we damage after that.

Aren't we just using a glorified railway line, and a couple of million superconductor magnetic impulse driver units? Solar powered of course, because we are environmentally aware, crazy people. Oops, I mean scientists.:laugh: