Solidifying the Last Snowball Earths
The first chapter of Genesis describes the remarkable transformation of Earth from uninhabitable and hostile to habitable and teeming with life.
Some of the events in that transformation required major stresses to the planet. For example the formation of continents resulted a couple billion years ago from an epoch of substantial tectonic activity. Now it appears the planet’s ability to support multi-cellular life also necessitated a severe global cooling.
Periodically, glaciers advance from the poles toward the equator. During the most recent advances 10,000–30,000 years ago, glaciers almost completely covered Canada and extended into Washington, Montana, and most of the upper Midwest. As extreme as this glaciation event sounds, scientists continue to find evidence of a far more dramatic ice age that occurred six to eight hundred million years ago. According to geological evidence, glaciers reached down into the tropics and may have completely covered Earth’s surface. Scientists refer to these periods of extensive ice-cover as “snowball-earth” events.
The Cryogenian period of Earth’s history lasted from 850 million to 630 million years ago. Two snowball-earth events occurred during the Cryogenian, namely the Sturtian and Marinoan glaciations. Although the scientific consensus acknowledges that the Sturtian glaciation reached low latitudes, the evidence does not clearly show whether it completely covered Earth or not. Greater understanding of this tumultuous period in Earth’s history requires more precise measurements of the timing and extent of the major events. A recent analysis of rocks from Canadian soil adds some of the necessary precision.1
The rocks from northwestern Canada contain volcanic material interbedded with glacial deposits that date to the Sturtian period. Using the uranium-lead (U-Pb) dating technique, the scientists dated the glacial deposits at 716.5 million years old, providing a precise date for the Sturtian period. Analysis of the magnetic inclusions found in the rocks indicates that the volcanic material formed near the equator. Thus, indicating that the Sturtian glaciers reached near the equator. Over the last 700 million years, crust material from the equator drifted northward as the glaciers receded.
The results of this analysis help solidify the evidence for massive, potentially life-exterminating events taking place throughout Earth’s history. They also provide a more detailed understanding of the sequence of events leading up to the most dramatic changes in life on Earth, i.e., the tremendous increase in complexity during the Avalon explosion and Cambrian explosion. The fact that these events did not exterminate life on Earth, but rather prepared the planet for more advanced life, comports well with the idea that a supernatural Creator was preparing Earth for humanity’s arrival.
- Francis A Macdonald et al., “Calibrating the Cryogenian,” Science 327 (March 5, 2010): 1241–43