sub-surface

Broad completely misses the point that sub-surface demolition makes plugging the well “from the top” unnecessary.

Large fields of oil and natural gas are the most important sub-surface assets.

Gypsum—a calcium sulphate—occurs naturally in many sub-surface clays, often in well-defined crystalline masses.

The sub-surface circulation in the Atlantic may be regarded as consisting of two parts.

The only safe thing appears to be the sub-surface irrigation plan, for which, fortunately, there is plenty of room on our lot.

About three inches below the soft snow was a sub-surface crust strong enough to carry the bodily weight.