Present that our planet was held down by a cold, and over ice desert to which the landscape has turned, furious norths storm. So the Earth in a glacial age - from 1,7 million to 10 000 years ago looked.
Almost any corner of globe stores reminders on process of formation of the Earth. The mountains concerning the sky, running a wave for horizon hills, a stone taken by the person for a city building, - at each of them the story.
During geological researches these helps can tell about a climate considerably differing from the today's. Once our world has been held down by the thick cover of the ice laying to a way from frozen poles to equator. The Earth was a grey and gloomy planet in a vice of a cold which was born from the north and the south by snow storms.
the Frozen planet
On character of glacial adjournment (settled oblomochnogo a material) and the surfaces erased by a glacier geologists have concluded that actually there were 7 glacial ages. The first has begun about 2300 million years ago, still in dokembrijsky the period. Last also is better the studied took place between 1,7 million and 10 000 years ago in plejstotsenovuju an epoch. It uproshchenno name a glacial age.
At that time glacial streams, gradually moving ahead from the North Pole, have covered half of territory of the North America and Europe. And though the earths to which managed to avoid this ruthless vice, usually too were cold, the winter reigned not on all planet. Around equator there were extensive areas of rainforests and deserts. These oases of heat have played a considerable role for a survival of many kinds of mammals, reptiles and plants. The climate lednikovja as a whole too not always was cold. In breaks between approaches of ices weather in some parts of a planet even was much warmer than the today's. In Southern England, for example, the climate was almost tropical. Fossilized remains allow paleontologists to assert that once on coast of Thames hippopotamuses and elephants wandered.
These periods of thaw - known as mezhlednikovja - lasted some hundreds thousand years before returning of colds. Distinguish two kinds of activity of glaciers: erosion and adjournment.
Erosion occurs, when the weight of moving ice erases soil on the way. Fragments of rocks brought by a glacier vypahivali in radical breed the whole valleys. Movement of ice and droblenogo a stone operated as the huge grinding car polishing under self the earth and creating the big furrows, named glacial shading. In due course valleys went deep and extended, getting the accurate U-shaped form.
When ice thawed, it left after itself(himself) heaps of fine-grained clay, large gravel and huge boulders, in the disorder scattered on huge territory. The most part of a landscape of northern part of Europe and the North America was generated during these processes.
the freezing Reasons
Scientists do not know till now precisely that causes an icing. Some consider that last millions years temperature on poles of the Earth more low, than when was for all history of a planet. Drift of continents - process owing to which continents gradually separate from each other could become the reason of it.
About 300 million years ago there was only one huge supercontinent - Pangeja. And though split of Pangei occurred gradually, eventually, moving of continents has left Arctic ocean almost completely surrounded with the earth.
Therefore, unlike the past, only insignificant mixing of waters of Arctic ocean with warm waters to the south is now observed. It means that it never well gets warm in the summer and is constantly covered by ice. Antarctica on the South Pole is too far from the warm currents, therefore all continent sleeps under ices.
Colds come back
There are also other reasons of a global cold snap. It is supposed that one of them - constantly varying angle of slope of a terrestrial axis. In a combination to the wrong form of an orbit it means that during any periods we are further from the Sun, than in others. And if the quantity of solar heat changes at least for percent, it can lead to a difference in temperature of the Earth on the whole degree. It is quite enough interaction of all these factors, that the new glacial age has begun.
It is considered also that dust accumulation in atmosphere as a result of its pollution can cause it. Some scientists assume that the century of dinosaurs has ended, when the huge meteor ran into the Earth, having lifted in air a huge cloud of a dirt and a dust. It could block receipt of solar beams through atmosphere of a planet and cause freezing of the Earth. Similar factors can promote the beginning of a new glacial age.
Some scientists predict approach of a new glacial age approximately in 5000 years. Others assert that it in general never came to an end! After all if last glacial stage plejstotsenovogo a glacial age has come to the end any 10 000 years ago quite probably that we are in an interglacial stage, and through any time ices can return.