A kettle hole is formed when immense chunks of ice are left isolated under layers of drift material as the glacier retreats.
(A kettle hole; is formed; T:when immense chunks of ice are left isolated under layers of drift material) (immense chunks of ice; are left; isolated under layers of drift material as the glacier retreats) (immense chunks of ice; isolated; L:under layers of drift material) (the glacier; retreats; )
A kettle hole immense chunks of ice immense chunks of ice the glacier
is formed are left isolated retreats
T:when immense chunks of ice are left isolated under layers of drift material
isolated under layers of drift material as the glacier retreats
L:under layers of drift material