It's of course all hypothetical because nobody has seen this happen, and it CAN'T happen. That is, the third picture down can't happen. You aren't going to get the curved rock to erode flat like that, not even as merely relatively flat as the picture shows. You'll get water runoff that erodes from high to low, exaggerating the vertical rather than smoothing it out, not sheets that erode flat. Which doesn't even happen when you start with a flat terrain. Not to mention that the difference in hardness between the layers will contribute further to a nonhorizontal result. The supposed flatness in ALL the geological diagrams of the creation of nonconformities SIMPLY CANNOT BE CAUSED BY EROSION.
As one of Lyell's illustrations demonstrated, which I posted on some time ago, what really happens is, yes, first Picture One, the laying down of the horizontal strata, though including the upper layers as illustrated in Picture Four as well -- all at once of course in the Flood, not according to Lyell but according to me -- but then Picture FOUR is what happens next, as the tectonic force pushes the lower layers laterally UNDERNEATH the upper layers that remain horizontal, eroding the contact between the two.
It's obvious to anyone who can really think scientifically.