Two motorcyclists were injured in separate crashes Sunday afternoon, one in Napa County and one in Sonoma County.

Napa County CHP officers arrived on the scene of a crash on Butts Canyon Road near Snell Valley Road, north of Pope Valley, about 12:40 p.m. where a male motorcyclist failed to negotiate a curve and went off the road, his motorcycle plunging about 50 feet down an embankment.

The man, who was not identified, was taken to a Vacaville hospital for moderate injuries, said Sgt. Mike Hagen. Drugs or alcohol use was not suspected.

In Petaluma, Sonoma County CHP officers responded to a motorcycle crash about 2 p.m. The unidentified man was driving on Tomales Road at Valley Ford Road when he crashed, said Sgt. Jason Bahlman. The motorcyclist was arrested on suspicion of driving under the influence.

You can reach Staff Writer Christi Warren at 521-5205 or christi.warren@pressdemocrat.com. On Twitter @SeaWarren.