Hello Sterling, All,
I do realize that the'craters' that I found were not, indeed,holes in the ground. However, the 'craters' that I found, would notbe depressions as you described.Each consists of features well over~15-20km across, the diameter necessary to create a complex crater, and would therefore consist of a central upliftwith a series ofconcentric (raised) ridges.
In order to view mine correctly, try zooming out to forty miles or so and having a look from up there. A much larger circular feature can be seen about the central uplift of my favorite candidate. (Visible at21 17'
10.89N 19 20'35.61E )This would be the area around the uplift that was shocked andmelted to some degree and also somewhat displaced.
The other consists of a large uplift and a single upraised ring about it, making it appear very similar to the large impact feature recently discovered near the Egypt-Libya border.
The features that you describe -- a hole in the ground with a raised rim --apply only to simple craters (which cannot, in most cases, at least here onEarth, exceed the limit of approximately 15-20km in diameter).Stefan's feature, measuring in at approximatelynine miles across, appears to be a rather large example (if it is actually a meteorite crater) of a simple crater.
Here's an informative site that you might want to read, as it has some rather good information on the subject.
http://www.lpi.usra.edu/publications/slidesets/impacts.html
also, try this:
http://www.solarviews.com/eng/tercrate.htm
Regards,
Jason
On 5/3/06, Sterling K. Webb [EMAIL PROTECTED]
wrote:
Hi, Stefan, List I think you got a crater there! The most impressive viewis to set your altitude around 30 or 40 miles up, orient yourself
to the NE of the crater, looking to the SW, then tilt the viewuntil your eye level is at about 4 miles up, and zoom in slightly.Wow! That is a classic crater. That view alone is convincing...almost. It needs to be seriously investigated.
Google Earth's view can be deceptive. I always trace therim and cavity of what appears to be a crater and read offthe altitudes to see it actually has a crater's geometric shape.
Parts of the Nicaraguan crater's rim are half a kilometer ormore above the floor. Jason Utas' candidate in Chad is an example of thedeceptiveness of visual features. Knowing the shape of acrater, we interpret the dark areas in the floor of what
looks like a crater as depressed and the bright featuresas central uplift and rim, but the dark features are actuallyas high or higher than the bright ones. When you tilt the viewyou see that the whole feature is elevated, like a squashed
mountain. Oddly, it seems to be set in a square embayment.Very strange. It doesn't look entirely volcanic but it doesn'tlook much like a crater, either.Kevin Forbes' Algerian feature is essentially flat and consists
of concentric rings of contrasting materials. Its appearancereminds me a lot of the much larger Richat Dome in Mauritania,whose crater or not status has been argued over for a long time.Currently, we don't think the Richat is a crater, but a domed,
layered structure sliced off flat to reveal its layers. His lessprobable structure looks more like a crater in the tilted view,but it is too battered to tell much. The Sahara is not kind,even to rocks...
Sterling K. Webb Original Message -From: Stefan Brandes
[EMAIL PROTECTED] To: Meteorite-list Meteorite-list@meteoritecentral.com
Sent: Sunday, April 30, 2006 1:21 PMSubject: [meteorite-list] meteorite-list] possible impact crater Hi list, has anybody heard about an impact crater in Nicaragua at coordinates :
13°21' N / 85° 57' W It´s about 12km in diameter and the town of Las Praderas lies directly in the center. It´s very good to see in Google Earth. As far as I know it´s definitely no volcano.
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