The first step of the scientific method is to pose a question or problem to be investigated.
Answer:
The Carboniferous era had large deposits of coal matter in the soil. However there was absence of decomposers which gave rise to increased accumulation of organic matter in the soil.
Decomposers make use of oxygen to breathe in the soil due to their existence as animals and not plants. They inhale oxygen and give out Carbon dioxide.
Absence of these decomposers mean increased level of oxygen due to its non usage and reduction in CO2 which is the end product of respiration for the decomposers.
Yes, the earth one was just one huge ocean.
The answer would be, a plate slides beneath another plate due to convection currents and gravity.
