The Loess Hills and the Niobrara Canyon

The soil underfoot across much of Nebraska did not come from rock wearing down in place. It blew in. During and after the last glacial period, prevailing westerly winds stripped bare sediment from glacial outwash plains and river valleys and carried it east and south, depositing it in thick layers called loess, a German word for loose. Nebraska sits within some of the largest loess deposits in the United States. In places the loess is one hundred feet thick or more. It is why Nebraska's farmland is so extraordinarily productive. The dust that was a catastrophe is also the soil that feeds a nation.

The Niobrara River cuts through the northern edge of this landscape, and here the geography does something remarkable. The Niobrara Canyon is not a grand canyon; it is a quiet one. The river moves northeast, carving through sandstone and chalk, and along its banks a botanist will find something that does not exist anywhere else in quite this way: a confluence of species that belong on opposite sides of the continent.

Eastern deciduous trees, paperbirch and basswood and bur oak, reach their western limit along the shaded north-facing slopes of the Niobrara Valley. Western plant communities, ponderosa pine and plains grasses, extend east far beyond their normal range along the drier south-facing bluffs. Rocky Mountain species appear in the cool ravines. Boreal plants that should be in Canada find the right microclimate tucked into the canyon walls. All of them meeting in a single river valley in north-central Nebraska.

Congress protected a seventy-six mile stretch of the Niobrara as a national scenic river in nineteen ninety-one. On a quiet morning in this canyon, the air is cool and the light comes in at an angle through eastern trees that have no business being here, except that the land invited them and they came.