The layers above would be not as old and the layers below would be the older layers.
Answer:
Number of bacteria required 
Explanation:
Given -
Size of each bacterium
micrometers long
These bacteria are arranged end to end.
The size of chain to be formed is equal to
centimetres
Let us say that in forming a chain of
centimetres nearly X number of individual bacterium are required.
hence, number of bacterium required to form
centimetres chain can be represented as

Number of bacteria required 
When water is transferred from land to atmosphere by evaporation from the soil and by transpiration plants.
Nottingham.ac.uk will help you with that question:)
It is necessary for the pancreas to secrete a high pH solution into the intestine in order to neutralize the acidity of the processed food particles [chyme] that are passed into the intestine and to provide a suitable pH for the enzymes in the intestines that will act on the processed food particles.