Transcript Coast ranges

Pacific
Mountain
System
Coast Ranges
North Coastal Ranges
South Coastal Ranges
Coast ranges
• Most Mountain peaks at around 4,000 ft.
• 550 miles long (North & South)
• Divided into Northern and Southern
Ranges at San Francisco Bay
• Proximity to ocean on west slope, keeps
temperatures cool, and fog common –
– Fog held there by mountains.
• Inland valleys, peaks have less coastal
influences
North Coast Ranges
• Run north of SF to Klamath Mountains, by
Eureka.
• Heavy summer fog keeps soil moist along coast
– Adds up 10 inches of precipitation
• Inland valleys drier due to rainshadow
– Bodega, Napa, Sonoma etc.
• Heavy Salt spray along coast
• Include mostly North/South running river valleys
– Eel, Russian Rivers
• Older than Southern Ranges.
• Includes higher peaks, some exceeding 7,000 ft.
North Coast Ranges
• Most Seismically active region in United
States
• In the 1990s, at least nine magnitude 6.0plus earthquakes jolted the North Coast.
• This amount of large quakes was higher
than in any other decade within the last
century.
Uplifting
• West coast constant rising up over last
several million years.
• Along with changes in sea level during Ice
Ages the uplifting of old marine / shoreline
terraces are moved from 100 - 1000 ft.
above sea level.
• Sedimentary layers get tilted in uplifting
and when saturated they may give way,
causing the frequent mudslides along
southern coast.
Eroded Marine Terraces
Montaña de Oro State Park
North Coast Marine Terraces
Northern Coastal Zones
• Pygmy forest: shallow soil with hard pan
underneath in sandstone.
– Water-logged in winter, dry in summer
– Costal fog keeps trees alive
– Restricted root growth stunts plants
– Bolander Pine endemic species, Pygmy
Cypress grows there as poor competitor.
• Closed Cone pines on uplifted dunessandy soils, cool wet climate with fog.
Pygmy Forest
• Shallow soil
• Hardpan layer restricts
root growth- stunting
trees
• Small plants but old with
mature cones, berries
• Needs heavy summer fog
to prevent drying out
Northern Coastal Zones
• Rocky intertidal – ocean and land meethigh diversity of algae and animals.
• Dunes (strand) drought-adapted
vegetation.
– Vines, deep roots, shifting sands
• Coastal Prairie: first terrace, uplifted dune
– Green year round, perennial wildflowers,
rushes, etc. Used for pasture for dairy cows
• Redwood forest – cool wet areas away
from salt spray
Northern Coastal Zones
• Mixed evergreen forest:
– Douglas Fir, Tanoak, Giant Chinquapin, Madrone,
Bay, Coast Live Oak
• Yellow Pine- Jeffery Pine
– High elevation or dry with serpentine
• Foothill woodland
– Blue Oak inland, Oregon Oak in coastal slopes
– Foothill pine, Buckeye, Redbud,
– Coast / Interior Live on north slopes
• Riparian
– Redwood, Bay, BL Maple, Doug fir, Torreya,
Dogwood, Alder , Willow
Biotic Zonation of North Coast Ranges
North Coast Range Geology:
• Arc islands that got accreted to North
American plate during the late Mesozoic
(65-150 million years ago).
• Has Franciscan rocks (shales and
sandstones) formed by rapid erosion
settling into marine basins, then uplifted as
arc islands.
• Franciscan Rocks
sedimentary marine
deposits uplifted
• Salinian Block formed
south of Sierras,
moved North 190
miles.
• Population of
salamanders, newts
traveled along with
rocks
• Now isolated as
separate species
Southern Coast Ranges
• Run from SF to Transverse Ranges, by
Santa Barbara
• Some peaks reach 6,000 ft. Taller peaks
in the southern end due to less erosion
• Larger, wider North - South valleys
– Salinas River Valley
– Nacimiento River Valley
• Strong slope effect: south-facing has dry
chaparral, north-facing has evergreen
oaks
South Coast Range Geology
• The Granitic rocks in the core formed as part of
Sierra Nevada batholiths moved north up to 300
miles north by San Andreas fault activity over
last 25 million years.
• Uplifting and placement of Southern Coast
Ranges above sea level over last 1-2 million
years, much more recent then Northern Ranges.
• Mainly composed of soft unstable sedimentary
rocks easily eroded
– Santa Cruz cliffs loose an average of a foot a year.
– Maximum record was 75 feet in one storm season
Coastal erosion
Serpentine - an Edaphic (soil)
ecological island
• Igneous rocks intruded into Franciscan rocks
and metamorphosized by heat and sea water to
green serpentine.
• named for serpent pattern of mottled snake skin.
• rich in Mg and Fe; Ni, Co, Cr
• low in Ca, Na, K
• These minerals leeching from rock make root
function difficult for plants, causing water stress
Serpentine communities:
Poor competitors survive on serpentine:
In North Coast Ranges: chaparral with Chamise
In wetter areas: Closed Cone Pines, Jeffery Pine
or Incense Cedar predominate
Specialists plants adapted to serpentine:
Leather oak
Interior Silktassel
Shrubby forms of California bay
Macnab Cypress in interior North Coast Ranges
Serpentine areas in
California
Banana Slug- Our State Mollusk
Very common in moist Coastal forests
Monarch Butterflies
West of Rockies, Adults
over-winter in coastal
valleys from Bolinas, to
Ensenada.
Eastern Monarchs migrate
to central Mexico.
Only known insect that
migrates over long
distances.
3000 miles to MX
660 miles AZ to CA
Winters
• Adults eat nectar- hard to find in winter inland,
easier along coast, Mexico
• Adults migrate, basically going extinct in cold
areas over the winter.
• Return to same trees as the previous year. Yet –
They are three or four generations removed
from previous years monarchs!!
– Migration is instinctive, not learned
• In spring they repopulate, laying eggs as they fly
back north, west. Offspring then take over
repopulation spreading the population back as
winter retreats.
Migration
Routes
Monarchs protected by Milkweed
toxins eaten while larvae
Larvae (caterpillars) eat Milkweed,
and accumulate the toxic cardiac
glycosides. The Monarchs are
immune but their predators are not.
Monarchs are protected by these
compounds from being eaten in
general. A few must be lost so
birds learn to avoid them.
Predators (birds) learn to avoid
adult monarchs by their coloration.