Radioactive decay is not a constant.

[FordGT90Concept]

The actual oldest "large body" ocean floor is in the western Pacific, near the Mariana Trench, and has been dated to 180 My. All continental crust is much, much older.

The crust is the thinest under the oceans so it makes sense that it would be the youngest. Likewise, the crust is the thickest on land and specifically, above-water mountain ranges so it makes sense that it would be the oldest.

My mistake, sorry. An increase in volume, and corresponding decrease in density necessarily means an ENORMOUS decrease in surface gravity over time (inverse square law - [corrected]).

Gravity is the result of mass, not density. The Sun and Jupiter are very gaseous (lower density than Earth) and they are still very massive. Earth would produce the same amount of gravity it does now if all of its mass were compressed into a pin-point. Likewise, Earth would produce the same gravity it does now if it were mostly made of gases. Unless there was a significant extaterrestrial impact with the Earth increasing Earth's mass, it is very likely the dinosaurs experienced more or less the same amount of gravity we do today.

 

[Steven Douglas]

The crust is the thinest under the oceans so it makes sense that it would be the youngest. Likewise, the crust is the thickest on land and specifically, above-water mountain ranges so it makes sense that it would be the oldest.

It's important to understand that oceanic and continental crust are completely different in composition, and that continental crust is thicker primarily because there is so much more of it in solidified form, but that it is also still counted as continental crust even in a partially or fully melted state.

Oceanic (mafic, or "dark") crust (0-200 My old), is comprised mostly of basalt and gabbro igneous rock created by partial melting of the mantle at the mid-ocean rifts, which cools to a thermal isolation thickness that averages ~5-7 miles (i.e., cools to a mean thickness, beyond which further cooling/thickening occurs very, VERY slowly). Oceanic crust IS upper mantle material, so there is much more of it overall, but only a small portion of which is actually solidified as ocean floor covering.

Oceanic crust is also denser than continental crust, so it seats lower atop the softer mantle below. Because all crust contracts and becomes denser as it cools (over millions of years) there is a distinct, even predictive age to water depth correlation in the deep oceans. However, age is not the main reason continental crust is so much thicker.

Continental (felsic, or "light") crust (average age 2Gy old) is much more varied in composition than oceanic crust, and also less dense, so that it rides simultaneously higher and deeper atop the underlying mantle than oceanic crust. Think of continents as giant deep-keeled "landbergs" - not in terms of ability to float about, but only in how they sit on the surface of the underlying mantle.

So continents are literally the differentiated, mostly silicate "scum" that floated to the surface of the earliest Earth. Continental crust, unlike oceanic crust, is ever buoyant, and does not sink, or even subduct (into the mantle, as in fully submerged) - at least not to any great amounts.

Following is a map I created based on the latest CRUST 2.0 map. It is simplified to illustrate thickness distribution of crust over the Earth, but especially thickness distribution within the continents, with the thickest mean averages >35km (and much thicker in those same areas) dominating the interiors, away from continental shelves.

There is a lot more to it, of course, especially as pertains to internal composition and formation of the continents. The important thing to note is that continental and oceanic crust are two completely separate beasts, each with distinct properties of their own, with thickness differences derived more from their unique compositions rather than respective ages.

Hope that helps!

 

[Steven Douglas]

Gravity is the result of mass, not density. The Sun and Jupiter are very gaseous (lower density than Earth) and they are still very massive. Earth would produce the same amount of gravity it does now if all of its mass were compressed into a pin-point. Likewise, Earth would produce the same gravity it does now if it were mostly made of gases. Unless there was a significant extaterrestrial impact with the Earth increasing Earth's mass, it is very likely the dinosaurs experienced more or less the same amount of gravity we do today.

The force of gravity is dependent in part on the distance between two massive objects, and while distant astronomical objects may often be treated as point masses, the surface gravity of a given sphere is very much dependent on its radius, given the formula:

g = G * M / r2 (surface gravity = Gravitational Constant times the Mass of the object divided by the squared radius) - as the radius gets smaller, the gravitational acceleration at the outer surface, measured in units-of-distance per units-of-time-squared, increases (G * M divided by a smaller squared number)

This where the inverse square law of gravity kicks in. Ready for some fun?

Example 1: I weigh 200 lbs. on our current Earth at 1 g. surface gravity. Half the radius of the same mass would mean four times the gravitational acceleration felt on the surface, giving me an equivalent weight of of 800 lbs.

Sound like a lot? It gets better. (or worse, depending on one's perspective)

Example 2: An Earth compressed to a pin-point would produce the same gravitational pull with respect to distant objects (e.g., the moon), but the surface gravity would be positively staggering, with human weight equivalent ramifications that would be much too large to comprehend. So let's move on instead to...

Example 3: Earth is now compressed to a 10km radius, or 20km diameter. It would completely destroy me, as I would feel an acceleration of ~406,433 g's at the surface, meaning that I, a mere 200 lb. man on our current Earth, would have a weight equivalent (the actual pull of the Earth against my mass) of more than 40,000 tons! I would be little more than a flat reddish stain - a very faint paint job, which would spread out very quickly over the entire very solid, mirror-fine and ultra-smooth surface.

And that is the problem with an Expanding Earth without a corresponding mass increase, because it must begin with an Earth that is far less massive. Otherwise, half the radius with the same mass would mean that a 9 ton T-Rex would weigh in at some 36 tons instead.

The thing to remember here is that each and every individual molecule that makes up the earth follows the gravitational inverse square law with respect to each individual molecule in your body. So the difference between the attraction felt by the chunk of Earth beneath your own home and a chunk of Earth somewhere on the other side of the globe is beyond enormous. Compressing the entire Earth would bring all of these individual molecules closer to your body all at once, thus concentrating/increasing the gravitational pull felt by you toward each and every massive atom simultaneously. If it was reduced to a pinpoint, your body would be drawn into that pinpoint at hyper-relativistic speeds.

EDIT: I found a site where you can have some fun with this yourself. Go here. The mass and radius is set for the Earth by default. After entering a different radius, click the equal sign to the right. Then click the "More units" button in the results window and it will display the equivalent g. force felt at the surface. Multiply that by your own weight, and that is what you would weigh.



EDIT II: I had some more fun with this, asking myself the question, "To what size would the Earth need to be compressed before it became a Black Hole?" (i.e., escape velocity becomes equal to the relativistic speed of light in a vacuum)

The answer: .00088 km, or 34.6456 inches, with a diameter of 69.3 inches, or 5' 9" across. So long before the Earth is compressed to a pin-point: I am six feet tall, which means that if I "stand" on an Earth surface, the diameter of which is three inches shorter than me, the soles of my feet are literally on an Event Horizon!

For the Sun to become a black hole, it would need to have a radius of 2.953 km, or just less than 6km in diameter.
For Jupiter to become a black hole - compress it to 18 1/2 feet in diameter.

 

[Hardrata]

Ugh sorry to be so late to the party and I hope Mr. Douglas is still around. You raise an interesting point about the expanding Earth theory that I had not considered or heard mentioned elsewhere. There is however one issue you may not have considered and that is one of angular momentum. Earth at the same mass, but smaller radius will spin much faster and have a much higher centripetal force effect, canceling out some of the surface gravity increase (or perhaps negating the increased surface gravity completely, I have not done the calculations). It was one idea I had for explaining the size of dinosaurs, they felt less gravity due to centripetal force increase on a faster spinning Earth.

Also, I had one idea for an explanation of an expanding Earth volume: radioactive decay. It appears that when a large atom decays, the daughter atoms occupy more volume space, when combined, than the original larger atom.