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The Grand Canyon is in the America state of Arizona. It is very long and very deep.The canyon’s sides show many rock layers.The rock layer at the bottom of the canyon is two billion years old. The layers at the top are young. They are a few million years old.In the Grand Canyon, the 540-million-year old rock layer is on top of 1.6-billion-year-old rocks.What happened to the missing rocks is a mystery? Scientists call the canyon’s missing rocks, the Grand Unconformity.Some scientists believe that ice eroded the rocks. Long ago, there was a time called “Snowball Earth”. Then, for millions of years, ice covered the whole planet.Now, American researchers have another theory. Over time, the Earth’s continents drift or move. Around 750 million years ago, there was one huge continent. Scientists call the single landmass Rodinia.Over the following 100 million years, Rodinia broke into large pieces. The break-up, the researchers say, was violent.The researchers think the break-up crushed the Grand Canyon’s “missing” rock layer. Then, rain and river water washed the small pieces of rock into the sea.
Manager’s Pro Answer: Yes, countries should work together to collect space junk. Countries that have launched satellites or space vehicles should help to clean up space. Their scientists can invent a way to do this. Also, cleaning up space is expensive. Therefore, more countries should pay for it.
Manager’s Con Answer: No, countries should not work together to collect space junk. The pieces of space junk are old satellites and launch vehicles. Some countries have created more space junk than others. These countries should find ways to collect their own space junk.