Silo summits

With plenty of cornfields but no frozen cliffs or falls in northern Iowa, climbers itching to sink their ice axes into the real thing have to journey to Wisconsin -- or hope they’re asked to climb silos. Don Briggs, a University of Northern Iowa outdoors instructor, crafts ice routes on four empty grain silos that tower 55 to 70 feet high at a buddy’s farm outside Cedar Falls. On Friday, about 40 college climbers (strictly invitation only) will tackle the vertical tanks at night in timed contests. “You’re looking at corn and cows and then turning around and swinging your tools again. It’s surreal,” says Shaun Lindsay, last year’s winner. Course record for a 65-foot silo is 23 seconds. Here’s how Briggs frosts his instant waterfalls:

* Start with a concrete, not metal, silo. Liquid slides off metal, and dark metal absorbs ice-melting rays.

* Make sure it’s plenty cold. Though water freezes at 32 degrees, thick, weight-bearing ice is guaranteed at 26 degrees.

* Drag a hose (which is what Briggs uses) and summit the silo’s ladder. Knot the hose to one of the silo’s rings with wire or heavy cord, turn the hose on full blast and leave it running so the water freezes like icicles. Scatter hay bales at the bottom for easy starts, and lean towering sheets of plywood between silos to shield them from wind and sun.

* Wait for the big freeze -- and hope it holds. A warming trend can send Volkswagen-sized ice chunks sheeting off silos.

* Grab an ax and go. This is a sheer vertical sheet, but wind can whip some crevices. Contestants ring the cowbell at the top and drink in views of the campus’ UNI-Dome, Cedar Falls -- and, yes, cornfields.

-- Ashley Powers