Planting grass and trees would stop erosion.
Answer:so if 4.6M = 4.6 billion years, then 1m = 1billion years so...
1m = billion years
1cm= 1000 million years
1mm= 1million years.
Explanation: you can solve this by doing conversion or write down each years value. Since Cm is lower than M, so we know it will be in the thousands of millions. Since mm is lower than cm it will be in the one’s place.
