Pergelic (L. per, throughout in time and space, and L. gelare, to freeze; meaning permanent frost).--Soils with a pergelic temperature regime have a mean annual temperature lower than 0°C. These are soils that have permafrost if they are moist, or dry frost if there is no excess water. It seems likely that the moist and the dry pergelic regimes should be defined separately, but at present we have only fragmentary data on the dry soils of very high latitudes. Ice wedges and lenses are normal in such soils in the United States.

8/10/98