Posted on 01/30/2019 7:30:18 PM PST by SunkenCiv
Normal faults are generated throughout the crater from the impact force. Fault blocks form along the crater walls, breaking off and sliding back into the crater following impact. Rocks around the crater rim fill in much of the crater as it collapses. Furthermore, resurge waves deposit large amounts of rock fragments in and around the crater. It is common for the crater to almost completely refill and subsequently be buried[.]
(Excerpt) Read more at geology.isu.edu ...
I've about had it with the failings of this out-of-date browser. I had to click 'blind' because it didn't draw the buttons, and instead of "edit" I got "post".
Normal faults are generated throughout the crater from the impact force. Fault blocks form along the crater walls, breaking off and sliding back into the crater following impact. Rocks around the crater rim fill in much of the crater as it collapses. Furthermore, resurge waves deposit large amounts of rock fragments in and around the crater. It is common for the crater to almost completely refill and subsequently be buried[.]
Alamo bolide impactThe Alamo bolide impact occurred 367 million years ago, when one or more hypervelocity objects from space slammed into shallow marine waters at a site that is now the Devonian Guilmette Formation of the Worthington Mountains and Schell Creek Range of southeastern Nevada; the event is named for breccias of metamorphosed crushed rock deposits, found as far as the town of Alamo, Nevada (the "Alamo Breccia"). This catastrophic impact event resulted in what is one of the best-exposed and has become the most accurately dated impact events; it occurred within the Frasnian age of the Devonian at about 367 Ma, a moment in time that was about 3.5 Ma prior to the Frasnian/Famennian extinction events, which it is unlikely to have affected.
You post the most interesting articles ...
Thanks! I just wish I wouldn't have screwed up that initial post like that. Ah well. The menu near the beginning has the rest of the related pages; the impact was 347 million years ago, in what is now Lincoln and Nye counties of Nevada.
I'd never heard of it either, and the initial identification apparently was due to, or by, Luis Alvarez, one of the fathers of the impact model of mass extinction. I went looking for "bolide impact" to see if there were any news items, and boom, there it was.
Whoops, make that 367 million years ago. Brain fart.
Here’s the story about the asteroid that hit Wetumpka, Alabama, 85 Million years ago...
http://www.auburnastro.org/wetu.htm
Thanks Alas Babylon! I may use that one as a topic. Wetumpka is the name the rock made when it hit. There's a crater in Texas that used to be an outdoor music theater.
Wetumpka is the sound the rock made when it hit.
Screwed that up.
There sure are a lot more impacts than one would think. Kind of scary. That “we won’t see it in our lifetime” line is absolutely ignorant, could happen any second.
http://www.auburn.edu/~kingdat/wetumpkawebpage3.htm#one
From Dr. King’s web page:
The town in Elmore County, Alabama, giving its name to the Wetumpka impact crater took its unusual-sounding name from a term in the Creek native people’s language: Awe-tum-cau@ which is derived from the union of Awe-wau@ (water) and Atumcau@ (rumbling; Read, 1984). Thus in Creek language, Wetumpka means Arumbling water,@ or alternatively Asounding or tumbling water.
These names are not entirely inappropriate for an impact crater that probably formed in shallow Gulf waters during the Late Cretaceous.
Thanks, I figured it was something like that, I was just making a joke.
That “we won’t see it in our lifetime” line is absolutely ignorant, could happen any second.
Exactly so. I knew someone (now deceased, some years ago now) who had a so-called genius level IQ (north of 150) who saw a magazine open on my desk (uh, I was reading that during my break) with an article about Chicxulub or something. He said that's impossible, those things burn up in the atmosphere. :^)
About 20 years ago (and this was before the number of known Near-Earths was anything like it is today) the odds of dying in an impact (given the number of known large impacts, which has also risen, over the lifetime of the Earth), were shown to be worse than the risk of dying in a plane crash. In part that's a tribute to how safe air travel is, of course, but *most* people don't expect to die in a plane crash, and by and large we are correct about that.
My view is that the mass extinction impacts and basically all or nearly all large impacts have been by NEOs, because those encounter the Earth (usually at great distances) on very regularly and routinely, and there are a lot of them (fewer than there used to be, due to kabooms into the Earth), and a lot of encounters for each one.
I've never had much use for the Nemesis model, wherein there's a currently undiscovered outer solar system body that disturbs the Oort Cloud every x millions of years, leading to a period of near misses and one big bombardment. That's just a uniformitarian's way of tryint to feel good about random catastrophes.
Absolutely. We tend to view our movement through the universe in a 2d frame of mind when in reality it is 3d. Not only are we orbiting the sun in our solar system, the solar system is corkscrewing us through stuff in rotation path as our arm of the galaxy circles the galactic center. And I would speculate that besides expanding, all the galaxies are also rotating around the center of the universe just like a galactic center.
All this compounds and greatly raises the probability and chances of running into something we can’t figure on. It’s like saying we have distances in the far north and the far south all figured out by using a Mercator projection map. They are not at all accurate compared to 3d globe distances and real distances. When figuring the movement of our earth we are only figuring in X and Y axis when in reality there are six or more.
And I am a firm believer that there are more than one physical universes, I think they could be just as numerous as the galaxies which adds another influence of movement. We just don’t see them yet and we will refuse to accept this possibility until we physically see it. It’s an antiquated flaw in our logical and reasoning skills that hinders discovery and reality.
Even with a 2D analogue, it's easy to see that it's a problem. Not sure if you've ever seen a spirograph, but even with wobbly pushpins, eventually the pen returns to the same point.
That is a fact. But unlike a spirograph which is on one plane, we are on a 3D spirograph ride. And like you say it might be a long time frame but everything returns to point A and starts the cycle all over again. Everything...
We are too short sighted. We don’t see things in the longer term time frame. It is a whole different perspective and reality when we do. This has all happened before, it’s not our first rodeo and it is time to accept the realities of long term history.
And it's so complex that invoking something like a dark companion of the Sun (or indeed, the probably imaginary Oort Cloud) becomes superfluous. As Han Solo hollered, "don't give me the odds!" So many asteroids have turned out to be made up of two or more asteroids, the odds of a collision happening (which is akin to finding a needle in a haystack from a mile away, using another needle) appear to be, uh, not well understood. :^)
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