1.   At its heart is Chankanaab Lagoon, renowned for its corals and limestone formations.

2.   Called stromatolites, they come in the shape of domes and knobs, spreading platforms and rising pillars embedded in limestone formations.

3.   Equal time is spent exploring the crimson-colored cliffs of Zion and the limestone formations in Bryce.

4.   He was referring to the eerily beautiful karst landscapes of southwestern China, where topsoil is scarce among the humpback limestone formations.

5.   The coral reef is a limestone formation made of the hardened skeletons of dead water animals called polyps.

6.   The rules are intended to protect the Edwards Aquifer, an underground limestone formation that feeds Barton Springs and supplies San Antonio with its only source of drinking water.

7.   The tour focuses on scenic rides along the coast of the Noto Peninsula, with its fishing villages, terraced rice fields and limestone formations.

8.   This is but one of innumerable caves dotting the limestone formations ringing Vang Vieng.

9.   In Lombardy try climbing the limestone formations at Lecco-Valmadrera, Grignetta, Val Seriana and Val Brembana.

10.   The labyrinthine nature of most limestone formations also makes karst management tricky, Smart warns.