Along the Way

The Lake That Ran Away

The next time you take Interstate 40 across Arizona, look hard at the desert north of Sanders. Ten million years ago, those parched sandstone plains were the bed of Lake Bidahochi, a vast wetland that flooded northeastern Arizona for the better part of an eon. From a point near St. Johns to the southeast, Lake Bidahochi stretched north and west to what is now the Grand Canyon, then just a meander in the course of the ancestral Colorado River.

It's easy to list staggering facts about Lake Bidahochi: 200 miles long, 100 miles wide. At its peak, it was as big as Lake Erie, and it persisted in one form or another for 4 million years. It swamped the Painted Desert. But Lake Bidahochi surpassed statistics. An oasis in an otherwise arid, empty quarter, the lake sustained herds of horses, camels, and llamas (species that would later disappear from North America) which swarmed to the lake's balmy shores.

Then, 6 million years ago, volcanoes arose throughout the region a couple hundred lifted straight out of the lake bed and in a few infernal moments of geologic time, their convulsions wrecked Lake Bidahochi. Already choked with lava, the lake dried completely when lava dams diverted inflowing streams toward the south and east.

Early one spring, my wife and kids huddled patiently by the side of State Route 77 north of Holbrook as I ran through all this. We were bound for Bidahochi, the small community on the Navajo Indian Reservation that gave its name to the long-gone lake. We planned to head west fromBidahochi toward Dilkon on Indian Route 15, then turn south on State 87, and return to 1-40 just east of Winslow.

Our route was to take us through the heart of the Hopi Buttes, remnants of the volcanic field that destroyed Lake Bidahochi. Usually you can see the buttes from the interstate, a dozen miles away, but a cold front swirled across the Colorado Plateau the day we visited. Although we were surrounded by them, the buttes were blanketed by fog. Occasionally one peak or another emerged from the mist then drifted back into it. The effect was of ships passing slowly in convoy. The mists were hotter 6 million years ago. And the buttes, actually the petrified necks of spent volcanoes, weren't anything like ships. Many of the Hopi Butte volcanoes were examples of a particularly violent type called "maar" by geologists. Maar volcanoes aren't content to ooze a little lava every once in a while; they explode in bursts pressurized by steam, the raw material for which was abundant in Lake Bidahochi and the ground beneath it. As the volcanoes cooled, breccia and other hard, dense rocks solidified in their necks. Once erosion carried away the rubble forming the volcanoes' cones, buttes were left behind like castings freed from a sculptor's mold. A big one is a thousand feet high, roughly circular, and half a mile across, depending on where you measure. Two calamities formed the lake: The continent's bedrock shifted, blocking drainage out of northeastern Arizona. At about the same time, a magma chamber formed deep underground. Later the magma would fuel the volcanoes, but initially the chamber had another effect: The earth above it sagged. Water, with nowhere to go, ponded in the resulting basin, and presto, Lake Bidahochi was born.

For the next few million years, the lake rose and fell in a leisurely cycle. Most times "The Lake" was actually a watery network of lakes, ponds, swamps, and marshes. Animals filled all its niches; wherever the lake provided space and food, some species moved in. Fish went below its surface, birds above. Beavers, weasels, and salamanders thrived in it. Shrews and raccoons, early horses, the aforementioned camels and llamas, all tried its waters. Some left their carcasses behind, others their tracks. Shorebirds marked clay beaches with dainty footprints now preserved in mudstone.

The volcanoes ended that tranquil era. While much of the lake filled with lava, as volcanic bombs burst overhead and globs of molten rock rained on them, the camels and their cohorts headed for other oases. Soon the lake was lost.

From Dilkon we drove southwest to State 87. We didn't mean to stop the interstate wasn't far; the evening promised to be raw but just south of the Navajo reservation, we came upon a sign announcing "Painted Desert Overlook."

At the overlook, sandwiched between clouds and desert, we had a decidedly two-dimensional view: limitless along the flat plain but completely blocked above and below. Even the varied palette of the Painted Desert was muted by the low ceiling of thick clouds. During half an hour, the quality of the light never changed but remained dull and diffuse.

Just when we'd concluded the sun would never set, or had already set, it dropped, all of a sudden, into the crack between the world and the sky. Instantly the clouds turned from pewter to silver, the air hazy with fog turned gold. Then in the distance, the peaks of the Hopi Buttes glowed red. And for a moment, the waters of Lake Bidahochi shimmered in the mist, way off on the horizon.