clay usually containing boulders or pebbles deposited by melting of ice; generally known as 'till'.

Glacial deposit consisting of boulders (grains varying in size) in a clay-dominated matrix. Boulder clay is laid down beneath a glacier or ice sheet and is typically unsorted, i.e. the grains/boulders are not in an arrangement of large at the base and small at the top of the sequence.

unstratified soil deposited by a glacier; consists of sand and clay and gravel and boulders mixed together

a sedimentary deposit of boulders, cobbles and pebbles set in a muddy matrix. Laid down by ice sheets.

SEE TILL.

Boulder clay in geology, is a deposit of clay, often full of boulders, which is formed in and beneath glaciers and ice-sheets wherever they are found, but is in a special sense the typical deposit of the Glacial Period in northern Europe and America. Boulder clay is variously known as till or ground moraine (Ger. Blocklehme, Geschiebsmergel or Grundmorane; Fr. argile a blocc1ux, moraine profonde; Swed.