Moraines
Snowball event: At the end of the Proterozoic Eon (750-600 million years ago), the earth was covered in ice and now. The formation of moraines during the deposition process of melting glaciers is important evidence of this event. Scientists have collected these rocks and found that some moraines formed in the equatorial region. This indicates that glaciers extended to the warm equatorial regions at that time. If even the equatorial regions were covered in glaciers, as the earth continued to cool, many land masses would have started to emerge from the oceans and become exposed and subject to weathering. Weathering consumes CO2 in the atmosphere. Therefore, as weathering increased, more CO2 was consumed. CO2 in the atmosphere was deposited in the ocean, resulting in a lack of greenhouse gases in the atmosphere and dramatic decreases in temperature, with the earth being covered in ice and snow. After millions of years, volcanic activity resulted in a large amount of CO2 returning to the atmosphere and resumption of the greenhouse effect. The snow and ice began to melt and the amount of reflected solar radiation gradually decreased. Temperatures on the earth began to rise and Snowball Earth ended, welcoming the formation of the Ediacaran biota.
