[stormer]

I'm afraid I don't understand your confusion. The passage states that when rock remelts and then relithifies, the isotopic ratio is a reflection of that ratio at the time the melting took place. As to your contention that the Earth was once smaller, I am unaware of any compelling evidence that supports that.

[ml/nj]

As to your contention that the Earth was once smaller, I am unaware of any compelling evidence that supports that.

Neither am I aware that it was ever smaller, and that's a problem for the conventional wisdom, isn't it?

As for isotope ratios, they don't change when something is heated or cooled. Consider ice that is melted and refrozen. The ratio of deuterium (Hydrogen with a single neutron in the nucleus) to simple hydrogen (with no neutron) to tritium (with two neutrons) will be the same before and after refreezing. This is pretty simple. What am I missing?

ML/NJ