what happened in the Cretaceous period.
Scientists tell us that it is impossible to invent a time travel machine. Too bad. It would be great fun to journey back for a look at our world as it was. But patient experts have dug up the details and we can imagine the past scenery in our minds. A week lasts only seven days, but it is hard to recall all the things that hap= pened since last Friday. In the past million years, 52 million weeks have gone by. And a million years is just a blink in the long story of our planet. The Cretaceous Period started about 130 million years ago. This page in the old earth’s diary lasted through roughly 70 million years. To visit it, we would have to travel back in time through more than three billion weeks or 60 million years. Naturally there have been a lot of changes and we would expect the Cretaceous world to be very different from the modern world. Take a deep breath, because those changes are more astonishing than you imagined. Even the world map is different. True, the Appalachian Mountains
