Rock thrown at Vic woman's car

A Melbourne woman is in hospital after a rock smashed through her car windscreen as she drove through the city's north.

Police found the 27-year-old in Thornbury in the early hours of Sunday with what appeared to be a lump of concrete in her lap.

They say she was travelling along Raleigh Street about 3am and the rock may have come from nearby roadworks.

The woman was taken to the Royal Melbourne Hospital to be treated for cuts.