Clarion, Roca Partida, and Shimata

Galapagos of Mexico; hot spot volcanoes on the sea floor

I. Map boundaries: 10 to 20 degrees North; 112 to 120 degrees West

II. Country (State): Mexico (Colima)

III. Overview

Isolated islands are noted for endemic plants and animals. The four Revillagigedo Islands formed on the East Pacific Rise or just to the west of the plate boundary between the Pacific and Rivera plates. Clarion Island, shown on this map, is 700 km southwest of the tip of Baja Peninsula and 1,000 km west of the state of Colima in Mexico. On Clarion, 14 of the 16 bird species are endemic, and there are an endemic lizard and snake. Approximately 26 percent of the plants are endemic. This endemism has earned the Revillagigedo Island chain the nickname of the Galapagos of Mexico. The rich marine fauna has been protected by the establishment of a nature reserve, but several articles not illegal fishing, and introduced sheep, pig, and rabbit, all of which compete with endemic flora and fauna, are the subject of control efforts.

To the east of Clarion is Roca Partida, or Broken Rock, which is essentially a sea stack sticking out of the Pacific Ocean. No vegetation is present, but the rock is used by nesting seabirds. To the southwest of Clarion is Shimata Seamount, which does not surface. It is believed to be a hotspot volcano of a geologically young age (The seafloor from which it rises is less than 20 million years old). Continue reading