I don't really understand what u r asking but centeral idea is main idea if that's what u r asking...
Answer:
• emissions reduction : Reducingnclimate change by reducing greenhouse gas emissions.
• sequestration : REMOVING CARBON DIOXIDE (CO²) FROM THE ATMOSPHERE INTO PERMANENT.
• ADAPTATION : REPONDING TO AND COPING WITH CLIMATE CHANGE AS IT OCCURES, IN EITHER A PLANNED OR UNPLANNED WAY.
• SLAR GEOENGINEERING : LARGE SCALE ENGINEERED MODIFICATION TO LIMIT THE AMONT OF SUNLIGHT REACHING THE EARTH IN AN ATTAPT TO OFFSET THE EFFECT OF ONGOING GREENHOUSE GAS EMISSION.
Well I'd say the answer is probably the layers were deposited in a river bed. I hope this helps.