YOUNG: It’s Living on Earth, I’m Jeff Young.

YOUNG: From time to time, we take the name of our program literally – and consider the nature of the earth we live on, its rocks, ridges and rivers. That’s when we pull out the book “Home Ground: Language for an American Landscape” – with its definitions of terms to describe the soil under our soles and the hills over our heads. Today, D. J. Waldie reads his definition of a term appropriate for the season – dead ice.

WALDIE: Dead Ice. The advance of even a continent-sized ice sheet eventually grinds to a stop. This stalled, slowly melting ice (think of a landlocked iceberg) is said to be dead. Dead Ice has a potent afterlife, however, despite its name.

Large tracts of remnant blocks of ice created the wet, jumbled pothole and hummock landscape of the coteau uplands of North and South Dakota. Debris in the ice and soil deposited on its surface was shed from the melting ice as a semi-frozen gumbo of gravel and earth to form dead ice moraines, where the surface of the dead ice was insulated by a thicker crust of sediment, variations in the melt of the underlying ice allowed the soil to collapse into landscape features as round as a doughnut, a ring of glacial debris, and boggy as a kettle, a sink formed when a core of dead ice surrounded by earth eventually melts. These features collect rain and snowmelt and are favored by migrating waterfowl.

YOUNG: D. J. Waldie is an author, commentator and contributing writer for Los Angeles magazine. His definition of dead ice comes from “Home Ground: Language for an American Landscape”, edited by Barry Lopez and Debra Gwartney.