Page 426 - Mexico Diving From the Caribbean to Pacific Isles

t most recently erupted in late January-
I early February, 1993. An earlier eruption
was on May 21, 1951; earlier eruptions prob-
ably occurred in 1905, 1896 and 1848. Mount
Evermann (Cerro Evermann) is the name giv-
en to the summit dome complex, in honor of
ichthyologist Barton Warren Evermann. The
island’s surface is broken by furrows, small
craters, and numerous ravines, and covered
in lava domes, lava flows and cinder cones.
T here is a naval station established in
1957, with a population of 250 (staff and tion, visited Santo Tomás and changed its
families), living in a village with a church,
that stands on the western side of Bahia
Vargas Lozano, a small cove with a rocky
beach, about 800 meters east of Cabo Regla,
the southernmost point of the island. The
station is served by a dock, a local helipad
and airport Isla Socorro. There is a freshwa-
ter spring about 5 km northwest of Cabo
Regla, at the shoreline of Ensenada Grayson
(or Caleta Grayson), an inlet. This is brackish crab (Gecarcinus planatus) which occurs on
or even covered by the sea at high tide No
evidence of human habitation on Socorro
exists before its discovery by Spanish ex-
plorers. Hernando de Grijalva and his crew
discovered an uninhabited island on 19 De-
cember 1533 and named it Santo Tomás. In
1542, Ruy López de Villalobos, while explor-
ing new routes across the Pacific, rediscov-
ered Inocentes and renamed it Isla Anublada
(“Cloudy Island”) due to the clouds frequent-
ly forming on the northern slopes of Mount
Evermann, and again in 1608, Martín Yañez
de Armida, in charge of another expedi-
name to Isla Socorro after Our Lady of Per-
petual Help (Virgen del Perpetuo Socorro).
T he native land fauna consists birds
predominating and mammals absent.
There is one endemic species of iguanid
lizard (Urosaurus auriculatus) and the land
islands throughout the region. Sheep, cats
and rodents were introduced to the island
by human activity; more recently, the locust
Schistocerca piceifrons has also established
itself on the island. Unlike the mammals on
Guadalupe Island or Clarión, their impact on
the local flora was minor, but cat predation
has had a drastic effect since the mid-1970s
due to the fauna’s island tameness, and the
locusts that swarm twice a year seriously
damage vegetation during that time. There
have been no recorded extinctions of plants
on Socorro; several birds have been drasti-
cally affected by cat predation. The Socorro
Dove, has gone extinct in the wild. Socorro
is an important breeding location for sev-
eral seabirds, many of which have here one
of their northernmost breeding colonies.