 |
 |
| August 2008 |
| Billie Silvey |
| Earth Environments |
| Mountains Mountains are formed where the earth’s plates collide. They make up a fifth of the planet’s surface, but account for only a tenth of the population. They appear on all continents as well as under the ocean. Even as mountains are rising as a result of volcanic action or the buckling of the earth’s crust, they are being worn away by wind, rain, ice and snow. The Appalacians are being eroded faster than they’re being built, while the Himalayas are in stasis. They’re being built up and worn down at the same rate. |
 |
 |
| Oceans With over 71% of the planet's surface covered by them, oceans are the largest habitat. Oceans regulate earth's weather. They support the greatest variety of life on earth, and they absorb carbon dioxide--an essential function for the preservation of life. Much of the deep ocean has yet to be explored. |
 |
| Forests Forests are of two basic types--coniferous and deciduous. Coniferous trees have small, needle-like leaves that stay green all year round. The northern coniferous forests or taiga cover Canada, Scandinavia, Russia and Mongolia--places where the summers are short and the winters long and cold. Deciduous trees have broad leaves to absorb sunlight. Those in colder areas shed their leaves in winter. |
 |
 |
| Jungles Jungles, or tropical rainforests, are complex environoments filled with life. Despite the fact that they cover only a few percent of the planet, they are the most diverse ecosystems on earth. Jungles around the globe are being destroyed at an alarming rate, endangering potential stores of medicines and areas capable of absorbing vast quantities of carbon dioxide, reducing global warming. |
| Deserts The distinguishing characteristic of deserts is a lack of water. Though some deserts are hot, others are cold, but because they are dry, they are open, treeless and deserted. A desert can be defined as anyplace where rain or snow fall more slowly than things dry up. |
 |
| Ice Ice covers an increasingly smaller portion of the globe, mostly near the poles. The poles are frozen because the planet is spherical and the sun is low in the sky. That makes shadows long and spread over larger areas. The poles have the greatest range of daylight hours throughout the year. The sun never sets in midsummer and never rises in midwinter. |
|
|
|
|
|
|