sandstone, and shale that can be seen in the mountains of the eastern Mojave Desert an
Basin and Range provinces (Figure JC.10) were deposited in shallow ocean waters along the
passive continental margin. Similar deposits extend westward into the Sierra Nevada and
Transverse Ranges, but have been highly deformed and metamor phosed by later events in
those areas. Paleocoic time, about300 million years ago, the passive western margin of
Laurentia began to change. The continental masses format during the fragmentation og
Radiniahad started to reassemble into the supercontinent know as Pangaea. The early
stages in this process involved collisions between Laurentia and several plates to the east to
create large continental masses. When Laurentia collided with Eurasian plate, Laurasia, the
large northern portion of Pangaea was formed by the combined masses. The trailing westrn
margin of aurentia was not directly involved in the construction of Pangaea, But the shift
from a passive to an active ontinental margin occurred at about the same time. In western
North America, there ic clear geologic evi-dance that convergent plate interactions exited in
the later period of the Paleocoic early Oceanic plate approachinthe western edge of Laurasia
carried island arcs and other rock bodies that eventually collided with the continental
margin. Ach collision resulted in a pulse of mountainbuilin in westrn North America was
replaced in mid Paleocoic timeby a raucous convergent plate boundary with rising
mountains, erupting volcanoes, and violent earthquake es. When Pangaea began to break
apart in the late Triassicperiod, the fragment that become modern North America began
moving wet as the Atlantic Ocean basin opened Geologic activity along convergent
continental margin intensified as the convergence increased This era of rapid plate
convergence, intense igneous activity, and widespread mountain building the Mesocoic Era
is generally known as the phases of geologic unrest during th Cordilleran Orogeny, but in
the California region, the most prominent was the Nevadan orogeny, a period of mountain
thaaffected the west from lata Jurassic through Cretaceous time (180 to 70 million years
ago). The Nevadan Orogeny was driven by the eastward sub- duction of several oceanic
plates beneath the advancing western ege of North America (Figure S C.11). By midJurassic time, about 180 million years ago, a single large oceanic plate, the Farallon plate ,
was moving under California. This subduction zone is called the Carillons subduction zone
after the oceanic plat that moved down- word into it. The Carillon seduction zone drove the
geologic evolution of California and adjacent for some 200 million years. Many of board
geological trends in California reflect the consequences of the Carillons seduction zone. It
was during the Navadan Orageny that California began to emerge as land along the west
coast of North Amrica. Magma generated in the Carillon seduction zone erupted onto the
surface to produce a linear volcanic arc that encompassed the modern Sierra Nevada region
as wellas are as farther north and south. Beneath the volcanoes, numerous bodies of
magma upward into the crut, setting the stage origin of the granite comprising the core of
the modern Sierra Nevada. Mesocoic plutonic rooks related to the Farallon seduction zone
There is no easy answer to this at all. “While recognicing the site’s importance, Swanson
said there are still “ambiguities” over precisely what it was. If said the store of artifacts
taken from the side and stored at the History Miami museum will provide specialists and
historians years worth of study and analysis. Carr, who works for MDM, which by law must
pay for the archaeological survey, said h has also recommended to his client that as much
as possible of the site be preserve in place. “If you have a necklace filled with pearls, what
makes it valuable is its entirety, not four or five pearls,” Carr said Preservationists not that
MDM took a change when it purchased a decade ago because it know the site was inside a
designated archaeological zone. Though the side was covered by asphalt parking lot for to
years, Carr and other