farmerman, What ever happened to the material that made the impact craters? c.i.
some craters(usually the big ones) have shown fragments at great depths > 1km, while others have shown no bolide chunks at all. Much of the space material gets incorp[orated into the 'strewn field' which is a term describing a circular explosive ejection field made up of glassy chunks of greenish melt rock that form teardrop shaped ballista. these melt rocks get blown 100s of km outward . The deeper bolides like the Vredefoort and Sudbury have punctured deeply into the mantle and have caused magma to rise close to the surface. this magma is deeper continental/core melts that contain many metals but predominantly iron and nickel. The noble metals i was prospecting in the Sudbury geologic province, were located in fumaroles and "hot water" deposits called pegmatite lenses, Here, the metals plate out at their 'freezing" temperatures which is about the same temperature as silica's freezing point. thats why gold miners are always looking for quartz 'veins". This is a brief description but the Poag book I previously mentioned has a lot of discussion about metals in meteorite hits and tektites and all kinds of related phenomena.
Are these metals from space similar to what is common on earth? c.i.
ci- the elements from meteorites are exactly the same as terrestrial minerals. however the metallurgy is often different. iron/nickel meteorites have characteristic changes in their crystal structures so that they show octahedral lattices on the polished and acid etched surfaces. These are called widmanstatten figures heres a link to some meteorite lingo
widmanstatten figures
Hmm. now I need to find out how to highlight these links, they blend in with the lettering.
ci. I muwst be doing something wrong. i checked my link and it sent me to netscape. well, anyway go to http;//www.meteoritecentral.com and follow the directions to the glossary of termws . theres a lot of other information there.
F'man, Is this the image you were trying to show? I went to the link and was amazed at the site. Worth bookmarking, that's for sure!
Here's a quick link:
Meteorite Central Introduction
"Widmanstatten figures
Octahedral figures that appear in most iron meteorites after slicing, polishing, and acid etching. These are caused by the intergrowth of kamacite and taenite. The photo below left of a Gibeon slice illustrates an example of the beautiful patterns that can emerge. "
Im glad it opened ok for everyone. i guess theres some thing that wont let me check a link when I post. I wonder if its something in the browser?
farmerman, Thank you again. When we were much younger, the subject of space usually meant the our sun, the moon, the known planets, the "milky way" and those popular North Star and the dippers. Having been to the southern hemisphere a few times, the viewing of the Southern Cross is now counted in my experiences on this planet. My visit to the Charles Darwin Research Center in the Galapagos last month whetted my appetite about evolution, because we were able to observe how the different environments of the islands affected the fauna and flora of the same species in different ways. This was most very noticeable in finches; there are 17 varieties of finches with different shaped beaks depending upon the food source on the islands. Our cruise ship, the Millenium, had a small library where I found the book, "The Map That Changed the World" by Simon Winchester. I started to read the book, and became engrossed in the science of Geology. This is the reason I got involved in this forum. Thank you all for your contributioins, especially to farmerman. And, Piffka, happy to see you got involved. I have saved that link in my Favorites for future reference. c.i.
Thanks, Farmer for correcting the date of impact. I wonder if there were any vertebrate survivors in that area. I suppose some tiny
creatures might have found shelter.
You have certainly had an interesting career and I'm curious you
haven't written a book yourself. It would be a great read.
I second ronmac's opinion; write a book, farmerman. c.i.
Ive been too much affected by technical writing. I dont think i could write to hold someones interests. If I could Id write my story about my work in the Northwest Territories from Baffin to Banks island. Id even title it after a line in a Stan Rogers Song , "A Land so Wide and Savage".
However, Im afraid Id start talking about the geology so much that Id lose evryone except the real DIW rocknockers.
Most of my writing, when I used to do nature articles for some Pa papers, was really hard for me, sort of like pulling your spleen out through your nose. A real birth experience, and, I never took criticism well. Thats the hard part, Im rather obsessive about everything i do..so, Ill stick to my water colors as my artistic outlet.
thanks for the prodding, I do appreciate the thought.
farmerman, If you can create words like "sort of like pulling your spleen out through your nose," I don't think your readers will be borned. c.i.
first I was glad to see this topic in the history forum, although it could also go under science or education.
second: For one writer's view of a link between history , fossils and mythology I suggest "The First Fossil Hunters" by Adrienne Mayor.
(and yes, I'm not just paleobarbie, but a paleo educator as well...)
: )
hey cool, paleo. Welcome to a2k.
paleobarbie, WELCOME to A2K. Look forward to your contributions. c.i.
Hi PaleoBarbie -- (Welcome!) Sounds like an interesting book, the subtitle helps to explain it: "Paleontology in Greek & Roman Times". That's a theory I've wondered about before -- all those stories of strange creatures. Thanks.
