 Several lines of middens formed as people moved back and forth in response to variations in the sea level in the Sound.As the climate shifted into a cooler period, sometimes called the Vandal Minimum, sea levels fell to the point that Pine Island Sound no longer supported a fishery adequate to the needs of the Pineland population.Sometime during the 9th century, Pineland and other population centers along the west side of Pine Island, such as Josslyn Island and Galt Island, were abandoned in favor of sites with access to deeper water on the barrier islands, such as the Mark Pardo Shellworks Site, and on islands on the west side of Pine Island Sound, such as Useppa.