 As the glacier retreated, sea levels dropped substantially, as low as 180 feet below what we now recognize as the coast of Maine.For the next thousands of years into the present time, the sea level has slowly raised into what we now recognize today.As the slow rise of sea levels changed the landscape and created Maine’s large littoral zones recognizable to humans today, the Archaic Period of human culture was taking place from about 3,500 to 9,000 years ago, characterized by cultures who started to exploit marine resources.