Here are 2 sites for you to learn more about these early trees, the fossils of which can be found in abundance in the state of Pennsylvania. The last site will explain how Archaeopteris dramatically changed the earth with its extensive root system. I have prepared this site in a well-organized format so that anyone interested in finding answers to specific questions about rainforests will probably find the appropriate leads here. Anyone doing research on rainforests and who needs a place to begin their journey will also find this a good starting point. Deserts do receive rainfall, but on the average, they receive less than 10 inches of precipitation per year.
Moisture tends to be unpredictable and occurring in brief intervals from year to year.
Often, the rate of evaporation is greater than the amount of rainfall and sometimes rain actually evaporates before even touching the ground. For a more extensive study, including many photographs, visit the homepage of DesertUSA , and take it from there. Each year an area equal to 11 square miles of ice, or 50 billion tons of water, disappears from Greenland's ice mass and adds to world sea levels. In fact, sea levels have risen 9 inches in the past century, or .005 inches annually. Though Antarctica has long been a center for scientific study for the possibility of global warming, the Greenland ice sheet is actually more sensitive to global cimate change since it is located in a temperate zone to begin with.