Snowball Earth, Among Other Prehistoric Disasters

I've always been interested in the origins and development of the Earth, both in its geological context and in that of the evolution of life.  I am also a subscriber to Netflix, at least the streaming Netflix which much too often comes up severely lacking with its offerings of movies and shows.  This time around, though, I found on it a four-part television series titled Prehistoric Disasters that explored the Earth's distant past through four key disasters that struck it over the eons.

The four "disasters" were the formation of the Moon through the collision between early Earth and a minor planet, the 25-million year long lapse into a completely ice-packed "snowball" status covering the entire globe some 650 million years ago, the eruption of a supervolcano in what is now Siberia causing a chain of events leading to excessive global warming and mass extinctions 250 million years ago, and the hypothesized collision of an asteroid with Earth about 63 million years ago causing the end of the age of the dinosaurs.  I was especially interested in that strange "snowball Earth"...

Earth throughout its span of existence has gone through an extensive cycle of ice ages, when ice glaciers would flow far south of the polar regions and into more normally temperate climate zones.  But 650 million years ago the ice passed a threshold of latitude and went on to cover the planet with ice, and very thick ice at that (several hundred meters).  The cause: depletion of carbon dioxide in the atmosphere due to loss of this gas as it combined with solid material through excessive weathering from the then-single, huge continental mass lying on the equator and then settled on the sea bottom, far away from the atmosphere.  The advance of the ice sped up the process of global cooling because the ice's reflectivity of sunlight was much higher than the liquid ocean's, sending the sun's heat back out into space instead of absorbing it into the Earth.  Life at that time, for billions of years ongoing as a matter of fact, was composed of unicellular organisms, mainly bacteria.  Nearly all of the species died out, leaving only those few that could adapt through evolution.  After the ice cover eventually receded from the heat generated by massive volcanic eruptions 25 million years later, life began evolving rapidly into more complex forms...but only after the "snowball" period.

By all accounts, the "snowball" period in our planet's past was a singular, nonrepeating event.  That bothers me a little and keeps me from completely accepting it, even though there seems to be empirical evidence that it occurred.  I would have expected at least of handful of other "snowballs", too, in the records.  But if it was truly the only time that Earth was completely encased in thick, thick ice...and for millions of years at that, then to me this has to be the most incredible period of its past.