( CNN ) -- Giant rocks came tumbling down a snowy Colorado mountainside early Monday , punching gaping holes in the interstate below , the Colorado Department of Transportation said . The rock slide at Glenwood Canyon halted travel on Interstate 70 between Glenwood Springs and Dotsero , about 18 miles east , according to the department . Glenwood Springs is about 120 miles west of Denver . It is unclear when construction crews will complete enough work to open at least part of the roadway . About 20 boulders struck the interstate shortly after midnight , the transportation department said . They ranged from 3 feet to 10 feet in diameter , with the largest weighing an estimated 66 tons , the department said on its Web site . About eight holes or dips were left on the interstate . Road underwiring was exposed and rock crumbles surrounded the damage , the department said . The largest hole measured 20 feet by 10 feet -- bigger than a full-size SUV . Rocks were scattered over a 100-yard stretch of the road . A steel guard rail and median barrier were also damaged . The damage resembles a major rock slide in the area back in 2004 , the department said .
Rock slide at Glenwood Canyon halts travel on I-70 between Glenwood Springs and Dotsero . It 's unclear when crews will complete enough work to open at least part of the roadway . Transportation department : About 20 boulders rolled down mountain shortly after midnight . Rocks were from 3 feet to 10 feet in diameter ; about 8 holes or dips left on the interstate .