MEDFORD — Birds perched on the jagged edges of the quarry flew up and out as the first horn sounded. After the third horn, the explosives planted in holes in a quarry wall were detonated. A loud boom was followed by a huge dust cloud that mushroomed up as 5,800 tons of limestone crashed from the wall to the floor of the pit.

The county's mineral mining committee stood on the edge of the quarry, about 600 feet away from the blast. The explosion was over in a few seconds, and committee members reboarded a school bus, which took them 200 feet down steep ramps into the Genstar Stone Products Co. quarry.


Committee members toured two Genstar pits off Route 31 between Westminster and New Windsor on Wednesday and walked through a nearby cornfield where The Arundel Corp. plans to dig a quarry.

The 10-member citizen committee is doing research before writing a report to advise the county on how land around areas where mineral resources existshould be used. Last month, members toured Lehigh Portland Cement Co.'s quarry in Union Bridge.


On the tours, they saw how the county's valuable supply of marble, concentrated in the Wakefield Valley area, is mined. The committee is charged with finding a way to balance mining company interests with quality of life for area residents.

At the bottom of one of the Genstar pits, company geologist Page A. Herbert said artists and landscapers often visit the quarry to hunt for pieces of the unusual pink marble that exists there. Some of it hasbeen chosen for a memorial for the Declaration of Independence in Philadelphia, he said.

College classes often come for tours because they can see various kinds of rock, faults, crystals and other geological formations in the walls of the quarry, which vary in color from gray to green to purple to pink, Herbert said.

Genstar, based in Hunt Valley, Baltimore County, makes and sells a variety of stone products used for building roads, roofs and driveways, among other things.

The company opened its first Medford pit, which measures about 11 acres, in 1957. The second, about 16 acres, was opened in the mid-'70s. The company has plans to join the two pits and eventually open a third, said James M. Mason, area manager.

Not far from the Genstar pits, where Nicodemus Road makes a 90-degree turn, The Arundel Corp. wants to dig a quarry. First, it must convince the county to rezone the land; efforts to do that have been mired in court since 1988. The company is based in Sparks, Baltimore County.

Wednesday, GeorgeB. Brewer, president of the company's Maryland Aggregates Group, showed committee members two sinkholes in the cornfield where the quarrymay be located.

One hole, which Brewer said could be seen on aerial photographic maps as long ago as 1952, measured about 50 feet across and was 25 feet deep. Another measured about 15 feet across and was 8 feet deep. The holes have been expanding over the years, he said.


Some area residents have expressed concern that mining operationsare causing more sinkholes. Owen Neighbours, an Arundel geologist, said the holes form after water gradually has dissolved the limestone,causing the ground surface to collapse.