In the rearview mirror, the Wasatch Mountains of Utah rise from the Great Basin. Low hills shoulder limestone caves, tucked into parched slopes of tall grass that roll toward Great Salt Lake like ancient waves. Long-gone shorelines band the hills like rings in a bathtub. A two-lane paved road cuts between dips in the knolls, edged by marshlands that spread through the Bear River Migratory Bird Refuge. On this February day, the chill has fogged into crystalline snow, blurring the marshlands, hills, and mountains until we lose sight of all distances, just the road around us. Almost imperceptibly, the air smells like rotten eggs.