Exploring abrupt climate change induced by comets and asteroids during human history

Saginaw Bay fingered by gravity data as ice impact feature

Davias and Harris at Cintos.org vindicated

Wow. The cascade of stupefying new discoveries continues. A paper published today in the Journal of Great Lakes Research provides evidence from gravity anomalies that Saginaw Bay in Michigan is a remnant feature of an impact into an ancient ice sheet. This and the recent discovery of Hiawatha Crater make for an interesting configuration. But gaze below at the monstrous concentric gravity rings surrounding Saginaw Bay…

From: “The putative Saginaw impact structure, Michigan, Lake Huron in the light of gravity aspects derived from recent EIGEN 6C4 gravity field model

Journal of Great Lakes Research, December, 2018

If you are interested in the Younger Dryas Impact Hypothesis, and not been hiding under a YD impact launched rock for the last decade, you have probably encountered Michael Davias’ and Tim Harris’ long contention that Saginaw Bay is an impact feature. They have done one hell of a lot of work on the subject, admittedly not in the field or the lab, but — from one pajama scientist to another — they deserve immense credit for intellectual bravery. Very, very hard to go to GSA conference after GSA conference, year after year, postering a nutty hypothesis not one single person in the huge hall will even entertain.

Good to see some interest in and vindication for Mike’s — and sidekick Tim Harris‘ — nutty idea. Gonna be a big Christmas over at the Davias household!

Michael’s page on Saginaw Bay

Old Tusk post 


Davias’ May 19, 2015 Presentation to Geological Society of American North-Central Section

4 Responses

  1. Some subjects don’t appear as full posts, so I have to throw them in somewhere.

    I ran across a news article that said NASA was quite interested in the asteroid named Psyche. Asteroids don’t always have names, so even that alone points to something special about Psyche.

    The article had a Youtube within it. A quick look will point out one reason Psyche is notable. https://www.youtube.com/watch?v=YnYqmoBn-_4&feature=youtu.be

    I bring it up because those deep craters illustrate something I argued in the past here. I argue that the planetary nebula theory is flawed because any impacts at the velocities of asteroids and comets and planets are going to REMOVE material from the two bodies involved, if not destroy one of them altogether and leave a huge crater in the other.

    Psyche seems to illustrate that, in spades. Look at those craters. 95% of the volume of the craters is GONE. No aggregation going in here, boss! EXCAVATION, not aggregation. Psyche speaks pretty loudly for my side of this argument. No planetary nebula could possibly build larger and larger bodies by them aggregating – sticking together somehow. They don’t. The smaller one obliterates a region of the larger one. If they are both around the same size, they pretty much have to pulverize each other.

    And what about the debris? The ejecta? That depends on the escape velocity. I found three values at three different web pages – ~0.18 kps, ~0.13 kps, and ~0.165 kps. (At about the velocity of bullets.) It is a matter of two factors – velocity of the impactor and materials properties of the target materials. Bullets do what they do – obliterate target materials – because of the energy the bullet has at the speed it is going, and the limitations of a thing called unit stress, as it applies to yield stength. If the unit stress from the impact exceeds the material’s yield strength, the material fails – i.e., it comes apart. That is what we see in all craters – the target material failed.

    Ejecta velocities range about 0.4 to 0.55 of the impact velocity, so anything impacting above 10 kps (relative velocity) would have an ejecta velocity of about 0.47 kps. And that 10 kps is a lowball conservative value. So, basically 100% of the excavated ejecta would never come back, having exceeded the escape velocity of the asteroid. It would fly off into space and keep going. So, so much for aggregation.

    I stand by my position of 4 or 5 years ago: Aggregation in a planetary nebula scenario is a wrong concept.

  2. Psyche’s full designation is 16 Psyche. Only the big ones – the early ones found – got both names and numbers, and a 2-digit number is notable. 16 Psyche is over 200 km i diameter, which is the main reason for its high escape velocity.

    I’d also offer up a scenario: Psyche does not have enough gravity to affect the orbits of nearby bodies. So, I believe that Psyche’s meetings with other bodies were essentially two bullets in flight hitting each other at random.

    A back of the envelope measurement on the screen tells me that the big crater is about 50-75 kms in diameter. That is about 40 times as big as Barringer Crater. And all that material is GONE.

  3. George –
    As I watched this CGI fly-by, I feel like I am seeing a kind of Carolina bays fly-by, but with circular craters instead of ellipses.

  4. i may not know squat about aggregation or excavation or planetary nebula but i do know that you cannot compare cartoon renditions of an asteroid and it’s craters to an actual crater on earth. NASA does not have a clue as to the size and depths of the craters on psyche yet. and their original estimation of it’s makeup has been changing over time. it now seems that it may be a rubble pile so that would change the dynamics of any impact. i also know that the ejecta from an impact with an asteroid is nothing like an impact of an asteroid or comet with earth. the main difference is GRAVITY so of course excavated ejecta will fly off into space from an astroid. not so with earth though. it is estimated that very little of the kt impact ejecta reached escape velocity. also, are you telling people that you made a computation of a cgi image of an asteroid that no one knows what it really looks like and used the answer in your argument plus if the “large crater” is 40 times the size of barringer then that means it is 1/4 the size of psyche. an impact that large would have blown psyche to smithereens, especially if it is a rubble pile. there is no way that i would believe your figures on the escape velocities of ejecta or impact velocities, especially with the way you have played fast and loose with facts in your posts. in fact, nothing you say makes one bit of sense.

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