A rockfall has shut off eastern access to the heart of Zion National Park/NPS

A substantial rockfall has limited access to Zion National Park in Utah, and the debris might not be removed from the Zion-Mount Carmel Highway before the weekend.

The rockfall, which came down early Wednesday, is on the east side of the highway leading up to the Mount Carmel Tunnel and was blocking both lanes.

"The largest boulder is estimated to be 200 tons, at 19 feet high by 20 feet long, and 15 feet wide," a park release said. "The second boulder is 100 tons, at 10 feet high, 10 feet long, and 15 feet wide. Road crews used a hoe ram to break up the boulders but the road has not yet been cleared."

Zion road crews, Utah Department of Transportation, and Federal Highway Administration engineers were assessing a section of cliff face above the rock fall for immediate hazards. It was possible additional rock will need to be removed from the cliff face before the road can be reopened.

This particular section of the road has seen rock fall periodically in the last 20 years, park officials said. Dave Sharrow, park hydrologist noted that, "the area that the rock fall occurred in, is a part of the Springdale Sandstone rock formation. There are cliffs that are near the road and because the road is carved into the side of the mountain, rock falls can and do occur."

Alternate east and west routes are available via Highway 59 from Hurricane, Utah to Fredonia, Arizona and Highway 14 from Cedar City, Utah, to Long Valley Junction and Highway 89. People traveling to the park may access the park by traveling east on State Route 9 from Interstate 15. All park facilities including the visitor centers, museum, and campgrounds are open and operating as normal.