Ancient global Ice Age which changed the face of Earth

The exploration analyzed how distinctive carbonate sedimentary rocks formed by the Ancient global Ice Age which changed the face of Earth.

A worldwide ice age over 600 million years ago adjusted the face of the planet, departing a barren, flooded landscape and clear seas, as showed by an investigation that may have significant implications for the evolution of complex life.

 

carbonate sedimentary rocks

The research, published in the journal Terra Nova, examined how distinctive carbonate sedimentary rocks formed over the course of millions of years after the global ice age.

The sedimentary rocks, much like the limestone in tropical oceans today, formed in oceans starved of sand and mud eroded from the land, the researchers said.

The sedimentary rocks, much like the limestone in tropical oceans today, formed in oceans starved of sand and mud eroded from the land, the researchers said.

How carbonate sedimentary rocks changed face of earth

The study calls into question previous suggestions that the formation of the characteristic rocks took place over a much shorter period of time, they said. Ancient global Ice Age which changed the face of Earth

“It was previously thought that these distinctive carbonate rocks were deposited over less than 10 thousand years, as the sea level rose when the ice that covered the entire globe melted, but we have shown that they were likely deposited over hundreds of thousands to millions of years following the sea-level rise,” said lead author Adam Nordsvan, a PhD candidate at Curtin University in Australia.

“There is already some evidence that suggested these rocks took a long time to form, but no one had been able to explain why this might have occurred,” Nordsvan said.

“What is intriguing about the period following Snowball Earth is that the planet surface was essentially completely renovated. It appears that the extended glacial period removed all the beaches, deserts, rivers and floodplains, and reset important Earth systems that took millions of years to recover,” said Nordsvan.

Effect of global Ice age over the Earth

Milo Barham, also from Curtin’s School of Earth and Planetary Sciences, said the findings may have important implications for the evolution of complex life. Ancient global Ice Age which changed the face of Earth

“The melting of ice sheets after Snowball Earth caused a dramatic rise in sea level, ultimately flooding the continents, driving a remarkable retreat of shorelines and the development of clearer ocean water,” Barham said.

“Researchers have long been aware that the timing of Snowball Earth and the development of more complex life seem to have coincided, but no one has really thought about how the oceans being starved of sediment might have helped ancient organisms thrive in the oceans,” he said.

Ancient Ice age - Snowball Earth

The earliest well-documented ice age, and presumably the most extreme of the last 1 billion years, happened from 800 to 600 million years prior (the cryogenic time frame) and some suggest that it created a Snowball Earth in which changeless ocean ice reached out to or close to the equator. Some suggest that the finish of this ice age was liable for the ensuing Cambrian Explosion, however, this hypothesis is later and controversial. A minor ice age happened from 460 to 430 million years back, during the Late Ordovician Period.

There were extensive polar ice caps at intervals from 350 to 260 million years ago, during the Carboniferous and early Permian Periods, associated with the Karoo Ice Age.

The present ice age began 40 million years ago with the growth of an ice sheet in Antarctica but intensified during the Pleistocene (starting around 3 million years ago) with the spread of ice sheets in the Northern Hemisphere. Since then, the world has seen cycles of glaciation with ice sheets advancing and retreating on 40,000 and 100,000-year time scales. The last glacial period ended about 10,000 years ago. Ancient global Ice Age which changed the face of Earth

The timing of ice ages throughout geologic history is in part controlled by the position of the continental plates on the surface of the Earth. When landmasses are concentrated near the polar regions, for snow and ice to accumulate. Small changes in solar energy can tip the balance between summers in which the winter snow-mass completely melts and summers in which the winter snow persists until the following winter. Due to the positions of Greenland, Antarctica, and the northern portions of Europe, Asia, and North America in polar regions, the Earth today is considered prone to ice age glaciations.

Evidence for ice ages comes in various forms, including rock scouring and scratching, glacial moraines, drumlins, valley cutting, and the deposition of till or tillites and glacial erratics. Successive glaciations distort and erase the geological evidence, making it difficult to interpret. It took some time for the current theory to be worked out. Analyses of ice cores and ocean sediment cores unambiguously show the record of glacial and interglacials over the past few million years. Ancient global Ice Age which changed the face of Earth

In between ice ages, there are multi-million year periods of more temperate, almost tropical, climate, but also within the ice ages (or at least within the last one), temperate and severe periods occur. The colder periods are called ‘glacial periods’, the warmer periods ‘interglacials’, such as the Eemian interglacial era.

We are in an interglacial period now, the last retreat ending about 10,000 years ago. There appears to be folk wisdom that “the typical interglacial period lasts ~12,000 years” but this is hard to substantiate from the evidence of ice core records. For example, an article in Nature argues that the current interglacial might be most analogous to a previous interglacial that lasted 28,000 years. Fear of a new glacial period starting soon exists. (Global Cooling). Ancient global Ice Age which changed the face of Earth

However, many now believe that anthropogenic (manmade) forcing from increased “greenhouse gases” would outweigh any Milankovitch (orbital) forcing; and some recent considerations of the orbital forcing have even argued that in the absence of human perturbations the present interglacial could potentially last 50,000 years.

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