Ah, so while there were ice sheets on every continent during these glaciations, there are actually quite a lot of places where sedimentary rocks survived the glaciations - perhaps as much as a fifth of the area of the continents (back-of-the-envelope, given that there is about a fifth as much preserved sedimentary rock per unit time prior to the end of the unconformity).
Generally a lot of these regions where rocks from the "missing" interval are well-preserved are at the margins of the (paleo)continents. This is for two reasons, as far as we can tell: (1) erosion by continental icesheets is more hit-or-miss near the margins; "hit" if you're in an outlet ice stream, but "miss" if you're not, since marginal ice tends to be "cold-based" and generally not very erosive at the margins outside of the outlet ice streams; (2) the paleo-continental margins are where all the tectonic activity was at the time -- and while tectonic uplift won't help any, tectonic subsidence can help a lot if it makes a basin subside below sea level (which will protect against erosion).
cbkeller, thank you so much for your answers!
Its rare I read such good answers on the grand scale implications of someone's research.
When you study plate tectonics, watch the Earth Story documentary [1], read Earth System History [2], Five Kingdoms by Margulis [3] or the books of Steven J. Gould [4] you get an overview of the history of planet Earth that geology, paleontology, biology and astronomy sciences pieced together in the last 150 years.
But then you never hear about the new breakthrough research that happens after these publications. But now I have learned about a new mayor piece of the puzzle by these comments of cbkeller [5], thank you very much!
If there is anything I could assist with, like writing complex (simulation) software in just a few thousand lines of code [6] for your research, you can reach me at morphle at ziggo dot nl.
Generally a lot of these regions where rocks from the "missing" interval are well-preserved are at the margins of the (paleo)continents. This is for two reasons, as far as we can tell: (1) erosion by continental icesheets is more hit-or-miss near the margins; "hit" if you're in an outlet ice stream, but "miss" if you're not, since marginal ice tends to be "cold-based" and generally not very erosive at the margins outside of the outlet ice streams; (2) the paleo-continental margins are where all the tectonic activity was at the time -- and while tectonic uplift won't help any, tectonic subsidence can help a lot if it makes a basin subside below sea level (which will protect against erosion).