Iceball Earth

More of my astronomical and space travel art can be seen in my DA "Space Art" gallery:

lexlothor.deviantart.com/galle…

Around 650 million years ago the earth was entirely covered by ice. Known as the period of the "Snowball Earth" the seas were glazed in pack ice all the way to the equator. All of the landmasses were clad in continental glaciers. Many artistic portrayals of this event in the geologic past depict a frozen planet as smooth as a billiard ball. This was certainly not the case. Continental drift was going on underneath the ice creating subduction zones. Volcanic arcs and great mountain ranges would have protruded out of the ice. There would have been geothermally heated areas free of ice and occasional dry valleys and mountains such as those which occur in Antarctica today. The surface of the iced over oceans would have been cracked and stirred by lunar tidal forces. The Moon was substantially closer to the Earth than it is today. The terrestrial day was also shorter so the tidal bulges swept around the globe more rapidly.

There may have been more than one similar period of complete ice over conditions going back to 775 million years ago. This interval of the late Proterozoic has been called the "Cryogenian". These events may have been triggered by a combination of effects. The sun was cooler then. Sol has been heating up over the past five billion years so it is unlikely that the earth will ever return to Iceball conditions. A runaway icehouse atmosphere probably resulted from the pumping of vast quantities of free oxygen into the atmosphere due to the proliferation of photosynthesizing cyanobacteria. The assembly and breakup of the earliest know supercontinent Rodinia also played a part. It has been postulated that volcanic activity releasing vast amounts of sequestered carbon dioxide into the atmosphere tilted the global environment back into a Greenhouse Earth. This could have resulted from continental crust overriding hot mantel plumes such as those that created vast lava flows known as the Permian Siberian Traps and Cretaceous Deccan Traps.

Another trigger mechanism for the end of the Marinoan Glaciation has been postulated. 580 million years ago an asteroid or comet struck what is now southern Australia. Within ten million years of the Acraman Event the marcoscopic Ediacaran life forms evolved.

What if the warm gaps and final end to the icehouse conditions had been caused by the collision of large asteroids or comets. Indeed there is some evidence that the eruption of lava traps may have occurred at the antipodes of major asteroid impacts. This is a phenomenon that has been observed on the surfaces of the Moon, Mercury and Mars.

In this image we see the surface of the terminal Iceball Earth from the vantage point of a large comet that is about to collide with Rodinia.

To see what happened next please view this picture:

lexlothor.deviantart.com/art/T…

art & text (c) John P. Alexander

2.5" x 3.5" art card rendered in Prismacolor pencils, Tombow markers & acrylics