Motorists caught up in a complete mess Wednesday afternoon on Highway 101 in Healdsburg apparently have a load of beer-making ingredients to thank for their trouble.

A truck hauling barley or hops southbound on the highway lost its load shortly before 4:30 p.m. when it hit a seam in the pavement and its gate popped open, releasing grain onto the southbound lanes and sending motorists skidding, the CHP said.

At least seven drivers lost control and crashed as they traveled across the broad swath of grain, Officer Mike Phennicie said.

"It's like driving on ball bearings," Phennicie said. "There's no friction."

Northbound traffic was affected when rubber neckers slowed to look, causing a chain-reaction, three-car crash on the northbound side that blocked all lanes of traffic there, as well, he said.

For one period of about 45 minutes, a single southbound lane was the only one open through the area, Phennicie said.

Traffic on the northbound side — the busier direction at afternoon commute time — was completely stopped.

But southbound was more dangerous, Phennicie said, because of a rise in the road that meant motorists came upon the scene at full-speed, without having seen what lay ahead.

Grain also was spilled on the west-side Dry Creek Road off-ramp, Phennicie said.

Caltrans crews were on the scene until 7 p.m. or later sweeping up on the road, he said.