The limestone caves in Dudley were carved out by the mining industry, hauling away 1,000 tonnes of limestone a week which was used to remove impurities from iron ore.

A team of experts from Kim Il Sung University, Kim Chaek University of Technology, the National Authority for the Protection ...

In other caverns, the concrete filling the pillars has spilled out to coat the limestone ground. Water showed traces of iron pollution by rust coming from the metal.

Engineer Guillermo D. Christy collects water samples while sitting next to a steel pillar filled with concrete, installed to support a part of the Maya Train track, inside the Aktun Tuyul cave ...

AKTUN TUYUL CAVE SYSTEM, Mexico -- Rays of sunlight slice through pools of crystal water as clusters of fish cast shadows on the limestone below. Arching over the emerald basin are walls of ...

Jess Marsh had spent 45 minutes crawling and twisting through the claustrophobic limestone tunnels of the Nullarbor Plain ...

AKTUN TUYUL CAVE SYSTEM, Mexico (AP) — Rays of sunlight slice through pools of crystal water as clusters of fish cast shadows on the limestone below. Arching over the emerald basin are walls of ...

Engineer Guillermo D. Christy photographs a steel pillar filled with concrete that was installed inside the Aktun Tuyul cave system to support the Maya Train track on the outskirts of Playa del ...

AKTUN TUYUL CAVE SYSTEM, Mexico (AP) — Rays of sunlight slice through pools of crystal water as clusters of fish cast shadows on the limestone below. Arching over the emerald basin are walls of… ...

Aktun Tuyul Cave System, MEXICO (AP) — Rays of sunlight slice through pools of crystal water as clusters of fish cast shadows on the limestone below. Arching over the emerald basin are walls of ...