Các đặc điểm vật lí của Trái Đất cũng như lịch sử địa lý hay quĩ đạo, cho phép sự sống tồn tại trong thời gian qua. Người ta hy vọng rằng Trái Đất còn có thể hỗ trợ sự sống thêm 1,5 tỷ năm nữa, trước khi kích thước của Mặt Trời tăng lên và tiêu diệt hết sự sống. | 1 ANCIENT RANGES Many ancient mountain ranges mark geological events in the distant past. The Caledonian mountains of Scotland were formed by a collision of continents more than 400 million years ago along a tectonic plate boundary that no longer exists. The mountains were once as high as the Himalayas but they have been worn down to form the heavily eroded landscape that now makes up the Scottish Highlands. 4 MOUNTAIN WILDLIFE The higher you go the colder it gets so being near the top of a high mountain on the equator is almost like being in the Arctic. The plants that live there have to be tough to survive and at really high altitudes nothing can grow at all. Mountain animals like the snow leopard have thick fur coats to keep out the cold and must be surefooted to move confidently through the rugged and often frozen terrain. 4 ERODED STUMPS WITHIN AIR Eventually all mountains are reduced to rounded stumps by the relentless forces of erosion. The Bungle Bungle range in northwestern Australia was once a high plateau formed from horizontal layers of sandstone. Over some 350 million years the For climbers every mountain is a challenge. Climbing can involve not only the dangers of ascending steep icy rock faces but also the problem of surviving at high altitudes. It can be freezing cold and the air on the highest peaks is so thin that edge of the plateau has crumbled under the assault of torrential there is barely enough oxygen to breathe. This makes climbing rain blistering summer heat and winter frosts to create these almost impossible so many mountaineers are forced to wear FAULTS AND RIFTS I FAULT PLANES Most faults are visible only within rocks but sometimes a fault plane is exposed As plate tectonics squeeze and stretch Earth s crust the rocks may snap. This causes the fracture lines known as faults. Vertical faults can form where one side of a fault plane has slipped down. Where plate boundaries are diverging great blocks of crust drop between pairs of vertical
