Major growth came in mid-century with the development of deep mining.

They're doing it in Utah for deep mining.

Until the invention of the steam engine this was the main restriction on deep mining.

Pliny also says that the method was used both in opencast and deep mining.

Many business closed as deep mining declined, and increasing numbers of houses stood vacant.

There is also evidence of deeper mining here.

However its main purpose is to regulate deep seabed mining.

The structure is designed to accommodate possible ground movements from future deep mining.

Also experts say that an earthquake can hit the region anytime due to deep mining.

Its main industry since the collapse of deep mining is now meat-processing.