What smoothed out Earth's surface for 600 million years ago - or was it already smooth?

I learned about new fascinating finding (see this) related to the geological history of Earth. During a geologically very brief period Earth's surfaces would have somehow lost its surface details such as rivers and lakes. This would have happened for 600 million years ago. Before this there would have been period of snowball Earth.

TGD provides different view about the renovation of the surface of Earth by loss of details and about the period before this change: snowball Earth hypothesis seems un-necessary. There were no oceans. The situation would have been the same as in Mars now. Water was in underground oceans as has been observed recently in Mars. One could deduce the story of Earth from what we know about Mars on basis of latest discoveries.

Cambrian explosion, in which complex multicellulars suddenly and mysteriously emerged took place about 512 million years whereas the loss of details is claimed to have happened about 600 million years ago. TGD based theory of expanding Earth assumes that Cambrian explosion happened because of geologically very fast expansion of Earth so that the radius of Earth increased by a factor 2. Amusingly, the radius of Earth would have been before the expansion same as that of Mars now!

Expansion would correspond to one fast jerk in the sequence of jerks, which replaces smooth cosmic expansion in TGD Universe: it is indeed known that astrophysical objects co-move in expansion but do not expand themselves (except by jerks). These jerks would be induced by reduction of length scale dependent cosmological constant by factor 1/4, or more generally, negative power of 2. The findings suggest that the expansion started about 600 million years ago and happened geologically very fast. Note that length scale dependent cosmological constant solves the basic problem of standard cosmology, which has killed many theories, also superstring theory.

Before this life would have evolved in underground oceans - the womb of Mother Gaia - shielded from cosmic rays and meteors. Oxygen and other important molecules could not leak out so that oxygen based life could evolve. In the expansion the core of Earth split into two parts (Mars has same radius as Earth and only single core) and the rotation of the outer core created ordinary magnetic field preventing oxygen and other important molecules to leak out. Otherwise the life at surface would not have survived. The surface of Earth split into pieces giving rise to continents and underground oceans gave rise to the oceans.

Consider now the mystery of lost details.

1. The surface of Earth before expansion should have looked very much the same as that of Mars now. Since there was very little water, rivers, lakes and this kind of features would have been practically absent. I do not know whether this is enough to explain the findings.
2. If the surface of Earth was stretched in the sudden expansion, the details of Earth's surface would have tended to disappear since gradients are reduced in the stretching. Whether the stretching really occured is however not clear: one could argue that the surface split into pieces like clay soil as it dries and formed continents.
3. The bottoms of oceans consisted of the magma from the interior of Earth and they should have been rather smooth. Also this might help to understand the findings.