Long ago, Greek writers created a list of the seven wonders of the world. But that list only included the wonders the writers knew about - the wonders of Greece and the surrounding countries. the writers did not know about all the wonders to be found in other parts of the world. People from Asia probably began arriving in North America about 40,000 years ago. to get there, they walked on sheets of ice more that 2000 feet (612 meters) thick. Eventually,...