What percent of green house gases do urban cities produce?

Geologists know that potassium-40 decays to argon-40, with a half-life of 1.3 billion years. if an analysis of a feldspar crystal in a sample of granite shows that 75 percent of the potassium-40 atoms have decayed to form argon-40, what is the age of the granite

Aletsch glacier is the largest glacier in switzerland and the largest found in the alps, a mountain range which extends from monaco in the east to slovenia in the west. currently, the aletsch glacier is retreating. under what circumstances would this glacier see growth instead of retreat? a decline in plate tectonics across the mountain range annual snowfall that exceeds yearly losses an increase in ablation in the southern valleys a rise in temperatures to that of a mediterranean climate

Why is terracing used in southeast asian agriculture?