ImagingGeek,
You wrote:
“Which is a round about way of saying exactly what I said. In the event you have an uneven distribution of mass perpendicular to the axis of rotation, there will be a force applied along the plane of rotation (i.e. perpendicular to the axis of rotation). In the event of a solid earth this force would result in precession of the earths axis of rotation.”
This is correct but what you stated originally was not, which was that
“In the case of a shifting core, it is going to shift to correct an inequity in the earths mass”
Your wrote:
“Assuming equilibrium is met (i.e. the earths center of mass is returned to its center of rotation), and the earth remains spherical, the gravity on the surface will be equalized - as in pangea will experience exactly 1.0G, and the ocean side will experience 1.0G.”
I responded:
“No, the shifting of the core(s), and therefore the shift in center of mass, has created the equilibrium. The center of mass will not coincide with the center of rotation. As long as Pangea remained basically intact, the differential surface gravity would remain the same.”
You responded:
“No, that is incorrect. With the core centered, and pangea off to one side, you start off in disequlibrium - mass is not evenly distributed along the plane of rotation, which creates a precessionary "force" across the plane of rotation. In this case you have "extra" gravity on pangea, due to the increased amount of mass beneath pangea, relative to the earth on average. As per newtons 3rd law, in the disequlibrium state described above, you also have an equal, but opposite force that would push the core away from the pressesion of pangea.”
My response:
You are making a basic logic error here......according to theory being discussed, the core(s) cannot be at center with Pangea formed. If our current continental distribution with core(s) centered were to reform into a Pangean state, the core(s) would gradually shift off center. Therefore, your initial conditions of “disequilibrium” is invalid. If you meant to state that as Pangea formed, the disequilibrium created precessionary forces resulting in a shift of the core(s) away from Pangea, then I would agree with that.
Re: Your drawing depicting the plane of rotation of Pangea:
Again, your first and second drawings depict an invalid condition (i.e., centralized core(s) with Pangea formed). I won’t comment on this one.
Your third drawing depicts the shifted core(s) along with Pangea.
You wrote:
“In the bottom case we have equilibrium - mass is distributed evenly across the plane of rotation, thus eliminating precessionary "force". Because the mass is now evenly distributed along the plane of rotation, surface gravity is also equal along the plane of rotation. Assuming a perfect sphere, this will be roughly 1G.
My response:
Not true. We do have equilibrium now that the core(s) have shifted off center and therefore, by definition, we do not have mass distributed evenly across the plane of rotation.
Therefore, surface gravity will not be 1G on Pangea but will be less depending on the amount of the core(s) shifting.
I wrote:
“Again, the reason why the oversized dinosaurs and sea reptiles and pterosaurs were able to develop was this lowered surface gravity and the reason they were gone near the K-T boundary was the rapid increase in surface gravity resulting from the breakup and dispersal of Pangea.”
You wrote:
“Sorry, that doesn't work for a number of reasons:
1) In disequlibrium, there would be less than a half-percent change in gravity on pangea. At equilibrium, that change goes away. In the former case the difference is so small (0.4%, or 0.004G) as to be meaningless in a biological context.”
My response:
Based on my last response, surface gravity on Pangea would be lower, the lowest near the equatorial regions. The ratio of current G to Pangea’s lowest G would be d^2/r^2 where r is the current radius and d is the distance from the shifted center of mass (due to the core shift) to the center of mass of Pangea.
You wrote:
“2) Pangea broke up ~150MYA, with the major breakup complete around 100MYA. The dino's went extinct and the KT boundary formed 65MYA. So the timing doesn't fit.
My response:
Pangea started to breakup earlier than 150mya. About 200mya the nascent Atlantic Ocean began to form accompanied by the massive flood basalt volcanism known as CAMP. It might be a matter of semantics, but “breakup” doesn’t fully describe the situation. There was rifting or separation, both latitudinally and longitudinally in different degrees well beyond 150mya. 65mya the continents were pretty much separated and moving apart rapidly, some rotating also. It is this rapid, non-uniform, primarily longitudinal movement that caused a corresponding shift of the core(s) back toward their original, centralized location. And, according to this theory, caused pulses of increases in G, resulting in extinction.
You wrote:
“(3) Assuming a slow breakup of pangea, the ~100MY period of time it took would have been more than sufficient for the dino's to evolve along with changes in gravity. Instead, we see even the largest of dino's making upto the KT boundary intact, and then suddenly disappearing.”
My response:
What you see is the largest (and tallest) sauropods disappear at the end of the Jurassic in North America and a shift of the largest sauropods (i.e., the titanosaurs) into S. America as Pangea moved north, thereby shifting the lowest gravity region south. The titanosaurs were different with wide lower bodies, shorter necks and wider stance, all evolutionary characteristics that could be the result of increasing gravity. As the K-T approached all of the larger dinosaurs disappeared. It is inaccurate when someone writes that the dinosaurs were thriving up to an instant in time.
You wrote:
“4) There is no known mechanism which could lead to a rapid breakup and leave the crust intact. There is also a boat-load of evidence for a slow breakup of pangea.”
My response:
Again it is a matter of semantics. “Rapid” in geologic parlance could mean millions of years.
The breakup of Pangea was rapid compared to its formation.
You wrote:
“5) The mineralogy of the KT boundary is consistent with chondritic meteorites, and not with the earths mantle, providing further evidence for the meteoric extinction model, and further evidence against a geological mechanism.”
My response:
I don’t deny that a meteorite struck the Earth around 65mya and neither does Vincent Courtillot who admitted this in ‘Evolutionary Catastrophes’, where he emphasizes the fact that hot spot volcanoes have accompanied almost all of the major extinctions. The Deccan Traps volcanic activity coincided with the K-T.
You wrote:
“6) There is a crater (Chicxulub Crater) which is both of the right age, and right size, as was predicted for the dino-killing impact. Once again, consistent with conventional science, and in direct opposition to your alternate answer.”
My response:
Yes, there is a crater there but where is the bone pile? If the cataclysm was so devastating, there should have been entire herds, rookeries, etc. of dinosaurs that were buried alive.......where are they? I don’t know of a single one discovered just below the clay layer.
You wrote:
“7) There is no geological evidence consistent with large-scale or rapid changes in the makeup of the earth around 65MYA.”
My response:
Not sure what you stating. 65mya was the point at which geologists/paleontologists decided to change the name of the era from Mesozoic to Cenozoic. Had to be a significant change at that time.
You wrote:
“8) There is no mechanism by which earths irridium, which is largely locked up in the core, to move to the surface. To get it to the surface would require sufficient force to destroy the earths core, or lift a portion of it to the surface. No irridium = no KT boundary.”
My response:
Courtillot believes iridium can come from hot spot volcanos. If I remember correctly, he gives examples of where iridum has been found but no signs of impact.
You wrote:
“9) There is no biological need for lower gravity - biophysical analysis of even the largest dino's (sauropods; see the references in my older post) shows that their physiology was more than sufficient to support their mass given earth-normal gravity. Same is true for the largest of flying petrosaurs - aeronautic analysis has shown that the second largest would have had no trouble flying at earth-normal. The largest isn't much bigger, and is expected to have very similar physics.”
My response:
I question the validity of the biophysical analysis that you cite. These are computer models and I’m sure you know what GIGO stands for. You were unwilling to accept the study done by a Japanese scientist using extant sea birds, which are probably as close to the flying, egg-laying, mostly fish hunting, believed-to-be warm blooded pterosaurs. I would put more faith in his study than a computerized model based on someone’s guess as to the flesh and bone, lifestyle, etc. of dinosaurs.
You wrote:
“ Like I've been saying, the evidence is against you model. The math shows that any variation in gravitational force will be small - a half % of 1G max. There is no evidence suggesting a catastrophic breakup”
My Response:
See my earlier post where I give the ratio of current G to G with shifted core(s). Surface gravity may have been 30% to 50% of current values.
Laze
