dirty work

Maynard Fosberg, UI's soil monolith king

by Diane Noel

Maynard Fosberg has almost certainly collected more soil monoliths than anyone else on Earth. He puts the number at about 350. Until he turned 50, the now retired UI soil scientist excavated the 5-foot columns of soil from pits he dug by hand—pits big enough to hold two men 6-feet deep. In 1970, he hung up his shovel for a backhoe.

Maynard Fosberg, fit at 86, still collects monoliths
and teaches his technique to others.
Photo by mark LaMoreuax.

Today, 86 and vigorous, he still collects monoliths. His quarry this spring is the soil under his horse pasture (he still rides) on the floodplain of Paradise Creek in Moscow. “Really, we don’t have a monolith that tells this kind of story in our collection,” he says.

The collection is the Maynard A. Fosberg Monolith Collection at the College of Agricultural and Life Sciences. Its 232 monoliths, most collected by Fosberg and his students, make it one of the largest in the world. The monoliths encompass the huge variation in the state’s soils—from gravels and sands left by melting glaciers north of Coeur d’Alene to windblown silts in the Snake River Plain—and a good deal of the variation in soils nationwide.

Mouse over the individual monolith to reveal legend.

Reading layers like historical tablets

Each monolith consists of a series of natural soil layers, and Fosberg reads each like a historical tablet. “It’s a record of the effects of climate, the effects of vegetation, the effects of parent material, the effects of time,” he says. “When you see a monolith for the first time, you can tell the plant community it’s related to, something about its climate. If you understand what you’re looking at, you can sort of reconstruct the history of that soil.”

The history of the soil under his horse pasture starts at the bottom with sands carried in Paradise Creek water from the very old granite on nearby Moscow Mountain. Next comes a thick layer of loess—silt blown in from Washington on prevailing winds. An ash layer 10 inches thick marks the date 7,700 years ago when Mount Mazama erupted in Oregon. On top of the ash lies a foot of silt eroded from the highly productive—and highly erodible—wheat fields upstream.

A monolith collected less than a mile away tells an entirely different story. Its 6 feet of mottled reds, tans, and whites date back 10 million years. “It’s a typical tropical soil preserved under this landscape,” says Fosberg.

To collect a monolith, Fosberg cuts a vertical slice of soil 8 inches wide and 2 to 3 inches deep extending from the soil surface down 5 feet or more into the subsoil, ties the intact soil section on a board, and lifts it out of the pit. Back at the lab, he works on the soil profile to reveal its structure and color, mounts it permanently on a plywood board, and stabilizes it with resins.

Bringing the field to the student

The monoliths are “really valuable teaching resources,” says UI soil scientist Paul McDaniel. “It’s like bringing the field in to the student.” Lining the walls of the first floor hallway in the Agricultural Science Building, the well-labeled collection is open to the public during business hours.

Fosberg specialized in soil classification, land use planning, and soil-plant relationships before he retired in 1989. Since then he has coordinated the Idaho state land and soil evaluation program in which more than 500 Idaho high school students compete each year. An endowment in his name supports that competition and provides scholarships for UI soils students.

“People are always saying, ‘What the heck are you doing? You’re retired. You’re working like you always did,’” Fosberg says. This summer, he intends to plant native Palouse Prairie plant species on 1.5 acres of his land, plants perfectly suited to the soil.

Contact Fosberg at mfosberg@GoVandals.com, or McDaniel at paulm@uidaho.edu.

Who cares what kind of soil it is?
A soil scientist’s bible, The National Soils Handbook lists more than 60 land uses—from septic systems to golf course fairways—and gives properties of a soil that can put limits on each. Some soils are too unstable for road building; some too wet for septic tank drain fields.

Soils under the UI, it turns out, are far better suited to farming than to building construction. Silty, they hold water well, but are weak and prone to frost heaving.

Extensive flooding in New Orleans after Hurricane Katrina illustrates potentially disastrous consequences of building on soils with severe limitations for construction.

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