The Lives and Deaths of Yellowstone’s Grizzlies

A three-year-old grizzly stands up to survey the countryside. (Paul A. Johnsgard)

By Paul A. Johnsgard

About fifty thousand years ago, as the northern hemisphere was locked in a global deep-freeze and the continental glaciers of the Pleistocene were at a maximum, a large land bridge that connected Asia and North America existed in the general region now occupied by the Bering Sea and Alaska, the so-called “Beringia” region. Across that corridor many mammals migrated from Asia over the millennia, including North America’s ancestral brown bears and, much more recently, the first humans.

One early influx of bears arrived in North America from Asia less than fifty thousand years ago. Some of these ancestral Alaskan brown bears apparently became isolated in island and coastal habitats by the last of the great glaciers, and the polar bear evolved from them. A later influx of bears from Asia produced the modern brown and grizzly bears (Ursus arctos).

Drilling into the Great American Water Machine

By James W. Goeke

It’s August of 2013, and I’m standing on a hillside in northwest Lancaster County, gazing into the distance through morning haze and waiting to hear that distinctive chopping sound made by large helicopters. In front of me a few feet downhill is something that looks like a gigantic Hula-Hoop with a metal box attached to one side of its curve.

The helicopter and the hoop represent a sea change in the way geohydrologists will go about the work of finding and defining aquifers. This technology won’t make drilling test holes obsolete. There will always be a need for human beings and drill rigs to establish the “ground truth” for what lies underneath a specific point on earth’s surface. But the equipment in that metal box does represent a revolution in how geologists will put together the descriptions and cross sections of the earth’s crust in a level of detail not previously possible. With ever-increasing certainty, geologists will be able to map the positions and compositions of previously “unseeable” layers of rock.

Immigration in Nebraska

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