Cause of Overflow Ice

Two conditions are required for the formation of overflow ice.

The first requirement is rather obvious--the air temperature must be low enough to cause freezing. Freezing of the ground surface and of the surface of a stream or lake forms an impervious layer that water cannot flow through. Once this happens, it can contribute to the second requirement for the formation of overflow ice.

That requirement is for the existence of water under enough pressure (i.e., with enough of a hydrostatic head) to rise to the surface. Even given a thick ice layer over stream or ground water, a strong enough hydrostatic head will cause the water to break through and overflow the surface.

If it is cold, the water breaking through will soon freeze before flowing far. Thus, peculiar glacier-like formations are built up, layer upon layer.

To see the effects drive out to the vicinity of the monument to Felix Pedro on the Steese Highway beyond Fox.