ST. PAUL — Activists plan to mark Earth Day by delivering over 6,000 petition signatures to Gov. Mark Dayton calling for a two-year moratorium on silica sand mining in southeastern Minnesota.

The petitions also call for creation of tough state-level regulations to protect air and water quality from the mining of silica sand, which oil and gas drillers use for hydraulic fracturing.

The Land Stewardship Project launched the petition drive in January. The group says southeastern Minnesota residents will be traveling by bus to the Capitol in St. Paul on Tuesday to deliver the petitions to the governor. The group says Dayton has the executive authority to enact a regional moratorium.

Dayton previously has expressed reservations about silica sand mining in the geologically fragile karst region of southeastern Minnesota.