Guides explain that it did not result from the action of water and streams like other limestone caves.

VOA: special.2009.12.07

The Portland Cement Association says the gas from the limestone is reabsorbed as concrete ages.

VOA: special.2009.12.01

Carbon dioxide is released in cement manufacturing when fuel is burned and limestone is heated.

VOA: special.2009.12.01

The walls were made of local limestone and bricks of sun-dried mud called adobe.

VOA: special.2010.04.26

The action of oil and natural gas created hydrogen sulfide in the limestone.

VOA: special.2009.12.07

a small amount of fertilizer and dolomite, a powder-like substance made from limestone.

VOA: special.2011.06.14

And it should be treated with limestone if the soil is acidic.

VOA: special.2009.07.07

The limestone developed about two hundred fifty million years ago.

VOA: special.2009.12.07

The surface is made of brick and limestone.

VOA: special.2009.12.13

There are many levels of granite, schist,limestone,and sandstone.

VOA: special.2009.10.07