Political instability would be your answer
One simple and easy way that scientists can accurately date fossils found is through the ground levels. When you take a big chunk out of the earth, you can see the changes in the texture in the "ground" Each "layer" represents a set of years. And as you get further and further into the ground, fossils become older and older.
Economic opportunities seems to be the driving factor for migration nowadays. An example of a group of migrants migrating from areas with a lack of economic opportunities to areas with more economic opportunities are Mexican immigrants seeking job opportunities.
Answer:
The rivers coming from the northern mountains carry alluvium with them and do the depositional work. In the lower course, due to gentle slope, the velocity of the river decreases which results in the formation of riverine islands.
Explanation:
