Travel Reference
In-Depth Information
CHAPTER
two
Natural History
Geology
B
IG
S
UR
'
S RUGGED LANDSCAPE
speaks to a tumultuous past, when ocean and rock col-
lided in a dramatic convergence. It is a geologically youthful region. In just 5 milli-
on years, Big Sur has been smashed between colliding tectonic plates, compressed by
massive faults, and rammed upward to form the jagged peaks, steep ridges, and deep
gorges of the Santa Lucia Range.
While the mountains themselves may be relative toddlers, many of the rocks bear
ancient origins, tens of millions of years old. The convoluted topography means that
rock types formed under radically different conditions lie confusingly side by side. An-
cient mountain ranges, seafloors, stream sediments, and molten rock form a jumbled
matrix that continues to baffle geologists.
The story for most of these rocks begins 130 million years ago, amid sediments
from an ancient mountain range 1800 miles southeast in present-day Mexico. In that
era, North America's western shoreline lay about where the Sierra Nevada stands
today, everything west was submerged beneath the ocean, and the Santa Lucia Range
did not exist. In the following millennia, westbound rivers deposited the sediments
along the coast, where these layers eventually solidified into sandstone, siltstone, and
limestone.
Over subsequent millions of years, a massive oceanic plate slid slowly beneath the
continental plate. The increasing depth and pressure melted the sandstone, siltstone,
and limestone, which slowly cooled and solidified underground as various types of
granite, marble, schist, and gneiss. The cooling process formed large crystals that lend
these rocks a salt-and-pepper appearance in the sunlight. Geologists believe that rock
types along the Big Sur coast and Santa Lucia Range share traits with granites of the
Sierra Nevada, comprising a group called the Salinian block.
The hard, crystalline rocks of the Salinian block comprise many of the prominent
high peaks of the range, such as Ventana Double Cone and Pico Blanco, as well as
many of the rugged coves, cliffs, and promontories along the Big Sur coastline, particu-
