The Ganga–Brahmaputra-Barak rivers deposit nearly 1000 million tons of sediment every year. The sediment from these three rivers form the Bengal Delta and the submarine fan, a vast structure that extends from Bengal to south of the Equator, is up to thick, and contains at least 1,130 trillion tonnes of sediment, which has accumulated over the last 17 million years at an average rate of 665 million tons per annum. The fan has buried organic carbon at a rate of nearly 1.1 trillion mol/yr (13.2 million t/yr) since the early Miocene period. The three rivers currently contribute nearly 8% of the total organic carbon (TOC) deposited in the world's oceans. Due to high TOC accumulation in the deep sea bed of the Bay of Bengal, the area is rich in oil and natural gas and gas hydrate reserves. Bangladesh can reclaim land substantially and economically gain from the sea area by constructing sea dikes, bunds, causeways and by trapping the sediment from its rivers.