[Rockhounds] Scottish and Irish rocks confirmed as rare record of 'snowball Earth'

[Kreigh Tomaszewski]

"The layers of rock exposed on the Garvellachs are globally unique.
Underneath the rocks laid down during the unimaginable cold of the Sturtian
glaciation are 70 meters of older carbonate rocks formed in tropical
waters. These layers record a tropical marine environment with flourishing
cyanobacterial life that gradually became cooler, marking the end of a
billion years or so of a temperate climate on Earth.

"Most areas of the world are missing this remarkable transition because the
ancient glaciers scraped and eroded away the rocks underneath, but in
Scotland by some miracle the transition can be seen."

The Sturtian glaciation lasted approximately 60 million years and was one
of two big freezes that occurred during the Cryogenian Period (between 635
and 720 million years ago). For billions of years prior to this period,
life consisted only of single-celled organisms and algae.

After this period, complex life emerged rapidly, in geologic terms, with
most animals today similar in fundamental ways to the types of life forms
that evolved more than 500 million years ago.

One theory is that the hostile nature of the extreme cold may have prompted
the emergence of altruism, with single-celled organisms
<https://phys.org/tags/single-celled+organisms/> learning to co-operate
with each other, forming multicellular life.

https://phys.org/news/2024-08-scottish-irish-rare-snowball-earth.html