The former of these two is considered a type of clay till which is made up of 50% sand, 30% silt, and 20% clay.[9] In the main area that has been searched for treasure along with the till lie bits of anhydrite, which become more competent deeper down. Researchers Les MacPhie, and John Wonnacott concluded that the deep deposits at the east end of the Island make up the drumlin formations.[9]