Creatures of the Ice

Any creature that survived the cataclysmic events at the end of the Cretaceous lived in a time of great opportunity. All the large predators and herbivores had been wiped off the face of the Earth. The remaining reptiles - Lizards, snakes, turtle and small crocodiles - carried on much as they had before. However, small, adaptle creatures that had until then spent much of their lives in hiding were suddenly presented with the opportunity to inherit the Earth. This Tertiary era, the third age of life on the Earth, has been the age of the mammals and the birds.

picture of Tertiary Era

Animals of Ice Age

Whoolly mammoth, wooly rhinoceroses, bears and buffalo roamed over the ice age tundra. These large creatures were well adapted for life at low temperatures, but they proved less adaptable than smaller mammoth mammals once the ice retreated.

Picture of Whooly Mammoths.

Part of the skull and the spectacular tusk of an adult wolly mammoth that roamed the tundra of England during the las ice age. This one wasfound in what is now part of the surburbs of London, England.

Picture of Mammoth's skull.

The skeleton of similodon, a sabre tooth tiger. This powerful cat had a large head, muscular shoulders and a short tail. it was a ferocious killer, using its huge, serrated canine teeth to slash into the flesh of its prey-mostly large mammals such as mammoth and bison.

Picture of Sabertootcat's Skeleton.

The great Freeze and surviving of the creatures

Following the break up of the supercontinent Pangaea, mammals evolved differently on each landmass. Then, 15 million years ago, an ice cap began to form on Antartica and sea levels fell. This allowed animals to migrate between the different continents. it continued to get cloder until, about 3.25 million years ago, variations in the Earth's orbit were large enough to trigger the first of ice ages.

Adapt or die:

As the polar regions froze, the ice reflected sunlight back into space and the Earth cooled further. When the higher latitudes cooled, equatorial reqions became drier, forming the basis for the savannah grasslands and deserts of today. Though some mammals developed thick layers of fat or fur to keep warm, the changing climate led to the extiction of many species. But one group used its ingenuity to keep warm, clothung itself in the skins of others and lighting fires. These mammals were our own ancestors.

Lands Of Ice

One of the starngest features of thw world that we inhabit is ice. No other subtance has a solid form which is less dense than the liquid form. To put it another way, ice floats. So, when the temperature drops and the sea begins to freeze, the ice is on top of the ocean , not underneath it. That is good news for life, since the ice creates an insulating layer which prevents the rest of the sea from freezing. In past ice ages, notably one about 700 million years ago, when sea ice stretched to the equator, lofe would have died out had the oceans frozen solid. the effects of ice on land are different. As water expands to become ice, it can shatter a rocky landscape, and a large ice sheet can even push down a whole continent.

Waiting for an ice age ?

Throughout the Earth's history, the temperature has fluctuated many times, perhaps due to changes in the Sun's activity or continental drift. The polar caps that exist today activity or continental of the last ice age, which began 3.25 million years ago. Since then, the northern ice sheet has advanced four times to cover large areas of North America and northen Europe. We may still be in an interglacial period today, waiting for the ice to advance once more.

Secret and the rivers of Ice

Secrets in the ice ?

The polar ice caps carry clues to the past. By drilling out cores of ice, scientists can can reconstruct the Earth's history. The thickness of the layers gives clues to the snowfall. Dust and chemicals in the ice keep a record of recent pollution and ancient volcanic eruption. Trapped within the ice are tiny bubbles of the ancient atmosphere.

Rivers of ice ?

Although solid, ice can slowly deform and flow. Vast areas of the Antarctic ice sheet are in motion, carrying thick slabs of ice from regions of high snowfall downhill towards the sea. One there, they eventually melt and are washed by the tides until giant icebergs break off, some of them as big as a small country. In mountainous regions, the snow packs harder.

U-shaped & iceberg

When a glacier finally retreats from the landscape, it leaves deep U-shaped valleys, some so deep that they are flooded by the sea, creating fjord like this one in Norway.

Air and water can sculpt icebergs into complex shapes. But 90 per cent of a berg is underwater, as ships such as the Titanic have found to their cost.

Frozen River and Glacier.

Like a frozen river, a glacier flows slowly through a rocky landscape shattered by ice. Line of rocky debris build upon its surface as it gouges out a deep valley.

Where a glacier meets the sea, there is a constant battle between ice and water. Sometimes avalanches of ice break off and crash into the sea, as has happened with this glacier in Alaska, US.

Survival of the fittest

whereas birds had develop insulating feather from the had scales of their dinosaur ancestors grew, mammals grew fur from soft, porus skin. This was just as well because the world's climate grew progressively cooler over next 50 million years. Mammalian evolution also saw experiments with size and ferocity. There were giant rhinos measuring 4 m at the shoulder and weighing 15 tonnes, and huge deer, such as the Irish elk. Sabre-tooth tigers and their marsupial equivalents lived along side a host of other mammalian monters, such as the wolly mammoth of Europe and the mastodons of North America.