Proterozoic

Proterozoic

Definition:

The Proterozoic, whose name is derived from two ancient Greek words meaning "early creatures", marks the beginning of animal life on earth. As after the Hadaikum and Archaikum third Aeonothem of the Precambrian, the Proterozoic is divided into three sections, namely those of the Paleoproterozoic, the Mesoproterozoic and the Neoproterozoic. It took a total of about two billion years.

Climate:

The climate in the Proterozoic is characterized by extreme contrasts characterized by strong volcanic activity and global icing. This era of geological history is dominated by two major glacial phases that have left a lasting mark on the chemical composition of the earth's crust and atmosphere. Traces of these glaciations are to be found as deposits of glaciers and sediments on several formations, the oldest are from the region of the Canadian Shield. However, it was only in the recent phase of the Proterozoic that a second global glaciation occurred, leaving its mark on much of today's Europe. This was scientifically proven to have occurred about 850 to 600 million years ago and presumably led to the scientists discussing snowball-earth modeling as covering all ocean surfaces with a thick layer of ice. Scientists assume that the absence of precipitation and escape of volcanic gas on the continents has led to a sharp increase in carbon dioxide in the earth's atmosphere and consequently a warming, ie a greenhouse effect. From this developed so-called Banded Iron Formations, which were formed by a sedimentary deposit of iron enriched in seawater.

Geology:

The processes of plate tectonics were already well advanced in the Proterozoic, because a consolidation of the continents had already taken place. It is believed that at the beginning of the Proterozoic already formed between fifty and seventy percent of today's earth's crust. The folding phases of the Proterozoic spawned the African, South American, North American, Australian, Indian, Eastern European, Siberian and Catholic Kraton as well as the Greenland Shield. In the Mesoproterozoic, the known under the name Rodinia, all land masses comprehensive supercontinent out, but began to disintegrate seven hundred million years ago. Its exact location is still highly controversial among scientists.

Flora and Fauna (plants and animals):

About 2.1 billion years ago, the first protozoa colonized the earth in the Proterozoic. Fossil finds confirm the existence of eukaryotic unicellular organisms such as different algae and other plant microfossils in what is now Michigan, where there was a Banded Iron Formation in the Proterozoic. Findings from China show that 1.7 billion years ago tangle-like forms of algae colonized the bottoms of the shallow seas. Eukaryotes already consist of many cells and a nucleus, are macroscopic in size, and require at least two percent atmospheric oxygen concentration for life. This indicates that the oxygen content in the atmosphere must have increased even before the onset of aerobic life on Earth. The spread of such eukaryotic creatures peaked about six hundred million years ago. The first primitive animal strains such as annelids and sponges also developed in the recent Proterozoic. However, the Snowball Earth effect led to a mass extinction in the Neoproterozoic, followed by an explosion of new animal life in the Cambrian.

Summary

The Proterozoic (Proterozoic) is a section of Earth's history that lasted from 2.5 billion years ago to 500 million years ago.

During the Proterozoic, the oxygen content in the atmosphere increased. This was caused by photosynthetic single-celled organisms in the oceans.

Guessing, the earth was temporarily completely frozen in the Proterozoic (Snowball Earth hypothesis).

The supercontinent Rodinia united all landmasses at the time of the Proterozoic.