They drill down to the shale, then go sideways and inject high-pressure water, sand or other material into the rock.

VOA: special.2009.10.23

Two-thirds of the white South remained in those classes we've come to call the yeoman farmers, the poor whites, or the sand hill farmers, as they were sometimes called.

三分之二的白人家庭属于这个阶级,我们称他们是约曼农民,贫穷的白人,或者没有地的农民

耶鲁公开课 - 美国内战与重建课程节选

Instead,you should use sand from rivers or from other areas of land that are not near the sea.

VOA: special.2009.09.14

For example, you can add sand to prevent tiny breaks or lines from forming in the finished product.

VOA: special.2009.09.14