 Finally, research by Lohe and others in western Norway has reported a sea-level low-stand at 13,640 calendar years ago and a subsequent Younger Dryas transgression starting at 13,080 calendar years ago.They concluded that the timing of the Allerød low-stand and the subsequent transgression were the result of increased regional loading of the crust, and geoid changes were caused by an expanding ice sheet, which started growing and advancing in the early Allerød about 13,600 calendar years ago, well before the start of the Younger Dryas.The current theory is that the Younger Dryas was caused by significant reduction or shutdown of the North Atlantic "Conveyor", which circulates warm tropical waters northward, in response to a sudden influx of fresh water from Lake Agassiz and deglaciation in North America.