boulder clay
deposit of clay, often full of boulders, formed from the ground moraine material of glaciers and ice-sheets
en-GB/ˈbəʊldə ˈkleɪ/
en-US/ˈboʊldɚ ˈkleɪ/
deposit of clay, often full of boulders, formed from the ground moraine material of glaciers and ice-sheets