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The Story of My As-Yet-Unverified Impact Crater
tetrahedrassface writes "When I was very young, my dad took me on a trip to his parents' farm. He wanted to show me 'The Crater.' We walked a long way through second generation hardwoods and finally stood on the rim of a hole that has no equal in this area. As I grew up, I became more interested in The Crater, and would always tell friends about it. It is roughly 1,200 feet across and 120 feet deep, and has a strange vibe about it. When you walk up to it, you feel like something really big happened here. Either the mother of all caves is down there, or a large object smashed into this place a long, long time ago. I bought aerial photos when I was twelve and later sent images from GIS to a geologist at a local university. He pretty much laughed me out of his office, saying that it was a sinkhole. He did wish me luck, however. It may be sinkhole. Who knows? Last week I borrowed a metal detector and went poking around, and have found the strangest shrapnel pieces I have ever seen. They are composed of a metal that reacts strongly to acids. The largest piece so far reacted with tap water and dish-washing detergent. My second trip today yielded lots of strange new pieces of metal, and hopefully, one day the truth will be known. Backyard science is so much fun. And who knows; if it is indeed a cave, maybe Cerberus resides there."
I'm kindof afraid that your backyard is going to become the first physical place to be slashdotted.
Could be a karst landform http://en.wikipedia.org/wiki/Karst_topography. Carbonate rock will react with water.
Cut the stone with angle grinder, polish the cut, show us the picture. Meteorites have quite distinctive texture.
You might be right at most of your points but there is no need to talk an enthusiastic person down like that. I for one am glad that people who haven't even studied this matter take interest in their local area and try to find out what it actually is.
I agree though that you should always go for the most logical assumption first.
[My apologies for the lack of links: Google is your friend. The editor is being a bitch.]
If it reacts with acid, it's carbonate (such as calcium carbonate, CaCO2). The classic test for carbonates is to dump a 5% solution of HCl (hydrochloric acid, available as muriatic acid in any hardware store) onto the sample; if it bubbles, it's a carbonate. (I know one geologist who calls this test "barbaric.") You can also use common household vinegar.
99.99% of all carbonates on the Earth are sedimentary. Usually, they form in shallow to medium depth water when microscopic critters with calcium shells die by the kazillions and fall to the ocean floor, where they pile into layers that give us things like limestone. There is one exception, however: Oldoinyo Lengai is a volcano in Tanzania that produces carbonate lava (the only carbonate-producing volcano in the world -- all the rest produce silicates, products based on SiO2). Someday I would like to see a sample of this igneous carbonate, because while silicates are really really important in geology, they're also really really common, and thus really really boring.
A relatively inexpensive bulk chemical analysis could tell you the exact composition of your samples, and you would probably find a pretty high iron content, which accounts for the trigger on your metal detector. My educated guess is the mineral siderite, FeCO3. It is common both in hydrothermal veins and in sedimentary formations.
Sinkholes can form when subterrainian water flows dissolve minerals (such as carbonates), forming a cave that later collapses. When this happens, you get a crater. And yes, you can get a pretty big one, depending on how deep the cave is.
So yes, it's a probably a sinkhole.
Remove the caps and hold to a mirror.
They'll just say it's a sinkhole or something, then insist that Global Warming is real and then pretend The Earth is really much older than the 6000 years old we all know it to be and that we all evolved from monkeys and that The Earth really goes around the sun, and that pi is bigger than 3. I wouldn't believe a scientist!
(Sorry. Am I being too mean here?)
Finding out a origin of such negative relief forms is a hard task.
1) Get a fine scale topographical map of it's surroundings. 1:10'000 is excellent, 1:25'000 could also work (depends on crater size). Look for any similar features around. Could this be a simple erosional form?
2) Go to nearest geological survey department and ask for surface geological map. Depending on Your location, it might be called "Quaternary sediment cover map". I'm not from USofA and thus have no idea if You will need to $$ to get it. If they offer also an geomorphological map, take that also. Those maps will help You to understand locations geological setting. You will be able to check possibility of ordinary karst or termokarst.
3) Compare craters location with known extent of Quaternary glaciations. In territories with Quaternary glaciations or close to glacial limits is possible to see termokarst depressions. They can be of variable size and form - starting from small, round crater-like forms up to large wally-like depressions filled with modern lakes.
4) If You want to describe any rock sample, You need to get a clean, fresh surface. Identifying rock samples by simply pouring an acid on it's surface might just reveal presence of calcite in soil and say nothing about rock it self.
5) Double check exact location in relief where You found those sock samples. Could there been some springs coming out or have been groundwater discharge location? Then it might be Limonite (bog ore) http://en.wikipedia.org/wiki/Limonite
6) If it's still not clear what it is - get an hand auger (soil sampler). I use One-Piece Edelman Auger. Make a profile line over that "crater" - sample on undisturbed land, on the rim, at the bottom etc. Get coordinates for exact location; photographs; describe color, wetness, anything You see or feel with hands (pebbles, sand, dust). Making correct description sill might need an training to get familiar with methods, still You will be able to tell if there's difference in soil composition on rims/bottom in comparison with surrounding territory (if crater is young enough).
Sorry form my language.
Looking at the pictures, the depressions to the north, the cutouts running north and south.. I would have to agree with the expert he consulted that what they have there are sink holes.
The metals could have even been dumped there, not as in a hoax, years and years ago as the site could have been a "garbage dump". Unless you know the history of the area, may never know for sure.
But that's the thing! He's not taking an interest! He's literally in the process of making up an urban legend.
I mean the parts are all there - "I've known about a place where weird stuff happens since I was a kid. I went to a well-established authority figure and he laughed me out of his office! Then I went back to the place where weird things happen and I found all sorts of strange artifacts! Oh my gosh! Tickets are $5 a person."
Seriously, give this guy another couple of years and he'll have found ancient Mayan ruins (nevermind the fact that the Mayans never came up here) complete with alien doohickies.
It's like this: taking an interest is looking at what's actually there. This guy is clearly only looking at what he wants to see. The overblown, sensationalist Slashdot summary is just a symptom of underlying delusions of mystery, and honestly fits perfectly with the generic urban legend narrative.
In fact, I bet you anything the geologist did absolutely nothing even remotely like laughing the poster out of his office - the poster e-mailed the geologist some pictures; physically being inside someone's office is a prerequisite for being laughed out of it, and honestly it doesn't work that at all if you interpret the sentence as a metaphor (I mean how do you know the geologist was laughing at you in an e-mail? Is it perhaps because at some level you know that your claims are, in and of themselves, laughable?). However, that phrase fit the story so perfectly we're expected to overlook this detail.
My father was a strawman, you insensitive clod!
The details are trivial and useless; The reasons, as always, purely human ones.