I guess I missed the article from 2008 that described the evidence for a post-Paleoprotozoic (1.2 bya - 330 mya) impact crater in the area of Santa Fe, New Mexico. A story this month in Astrobiology magazine says the original crater was probably 6-13 km in diameter, or about 5 to 10 times the size of Arizona's Meteor Crater at 1.6 km.
The University of New Mexico is organizing a public field trip for summer 2011 to examine the exposures that document the impact structure. [right, shatter cone outcrop. Credit UNM]
Ref: S. Fackelman, et. al, (2008) “Shatter cone and microscopic shock-alteration evidence for a post-Paleoproterozoic terrestrial impact structure near Santa Fe, New Mexico, USA,” Earth and Planetary Science Letters 270, 290-299.
Here is new even bigger impact theory;
ReplyDeleteEvidence supporting Kevin Mansfield's Earth Formation Hypothesis.
The Hypothesis:
Earth, as we now know it, formed from the collision of two similarly sized planets, called Heaven and PreEarth. Heaven had a radius about ninety percent that of PreEarth. These two, initially comprised a binary system (just like the Earth and Moon presently comprise a binary system) orbiting the Sun.
Like a bullet rips through the skin of an apple, leaving most of the skin unscathed, Heaven crashed through the crust of PreEarth, taking most of its energy into the interior, while leaving much of the crust unscathed. Now, imagine that the mass of the apple and bullet are so large (planet sized) that the bullet cannot escape their combined gravity. Then you have the hypothesized situation. Of course, as PreEarth swallowed Heaven, it greatly expanded in size. This expansion, however, did not leave the remaining crust unscathed.
The Evidence:
1) The hole in the Earth where the planet Heaven entered, i.e., the north west Pacific.
2) The impact mountains around the Pacific Ocean, i.e., the ring of fire.
3) Western impact mountains ripped off continental block.
4) The impact caused continental drift.
5) The theory predicts a single circular continent with splits, i.e., Pangaea.
6) The theory predicts oceanic crust very different from continental crust.
7) Warren Carey's evidence, is also evidence for this hypothesis.
8) Apparent sea-floor ages explained as geochemical gradient due to mixing.
9) The theory predicts Earth's core is rotating faster than its mantle.
10) The theory predicts Earth's magnetic field is rapidly decreasing.
11) The theory predicts/explains magnetic reversals.
12) The theory allows the force of gravity to have been smaller in the past.
13) Removes the thermal catastrophe.
14) The theory provides a decent power source for continental drift.
15) Animations of the expansion plus drift can be produced.
16) Provides a new theory regarding the formation of the Moon.
See http://preearth.net/evidence.html where each point above is expanded upon:
A brief history of the ideas.
Many of the ideas above were first presented in a public lecture, on November 2, 2008, at the Alexandra Park Raceway, Auckland, New Zealand. They were subsequently written up and published, on April 20, 2010, in the form of a 26 page paper. The preprint server arxiv.org refused to distribute this paper (clearly, the task of releasing preprints to the scientific community should be taken from those at arxiv.org and given to some responsible party). Consequently, toward the end of May, the website www.preearth.net was established to publicize the paper. This summary of evidence was completed on July 29, 2010.
Kevin Mansfield, has a BSc(Hons) from the University of Auckland (Auckland, New Zealand) and a PhD in mathematics from the University of New South Wales (Sydney, Australia).
From http://preearth.net