 Presque Isle is a recurved , sand spit that formed during the last glacial period , or ice age , when the Laurentide Ice Sheet advanced into the basin now occupied by Lake Erie , and , when it retreated to the north between 12 @,@ 370 BC and 12 @,@ 790 BC , left behind a moraine consisting of clay , sand , and gravel that initially formed the Presque Isle peninsula . The deposits are constantly being re @-@ worked by wave action and are gradually migrating to the northeast due to longshore drift . 
