Report Number: 107
Year: 2005

The Caves and Karst of Rota Island, Commonwealth of the Northern Mariana Islands

Rota Island, in the Mariana Islands, has the types of caves previously documented on other limestone islands in the Mariana Arc: Aguijan, Guam, Tinian and Saipan. Caves developed in the mixing zone at the edge of the freshwater lens are most common, with flank margin caves being most common. However, mixing zone fracture caves, apparently formed by mixing dissolution in pre-existing fractures are also common. The mixing zone caves of Rota reflect the interaction of eogenetic limestone, glacioeustasy, local tectonics and enhanced carbonate dissolution via mixing of disparate waters. The development of mixing zone caves on Rota is in agreement with the Carbonate Island Karst Model (CIKM). Rota has a few caves developed along the contact between limestone and volcanic rock. Rota also two extensive zones of vertical fissures developed along bedrock fractures.

Thomas "Monty" M. Keel
John E. Mylroie
John W. Jenson