File:Snowball Earth glacial rhythmites (Neoproterozoic; Mojave Desert, California, USA) 1.jpg

English: Glacial rhythmites from the Precambrian of California, USA.

The Snowball Earth Glaciations during the Neoproterozoic were the most significant ice ages that Earth ever experienced - two or three of them occurred in succession. The most extreme models describing Snowball Earth have glacial ice completely covering all continents and all oceans, even at the equator. Some models, called “Slushball Earth”, have Earth’s equatorial oceanic areas not completely frozen over. Each Snowball Earth Glaciation was followed by a super-greenhouse climate. The resulting sedimentary record of these “freeze-fry” events typically consists of glacial tillites and overlying cap carbonates. These units are preserved at many localities on Earth.

The rock seen here has repeating lamination patterns - these are rhythmites, probably varves. Varves are common sedimentary units in Pleistocene proglacial lake settings. This is a Snowball Earth equivalent. The rhythmicity reflects seasonal changes (summer-winter-summer-winter, etc.). Demonstrable annual layering is scarce in the sedimentary rock record.

The rock itself has been wind-eroded and wind-polished. Such rocks are called ventifacts.

Locality: Mojave Desert, southern California, USA