HomeMy WebLinkAboutGeologic Map:Lower Saratoga Hillside Index SheetGEOLOGIC MAPS
of the
LOWER HILLSIDE AREA
SARATOGA, CALIFORNIA
EXPLANATION
GEOLOGIC UNITS
Surficial Deposits
ARTIFICIAL FILL: EXCAVATED SOIL OR BROKEN ROCK PLACED BY MAN AT
A f VARIOUS DEGREES OF COMPACTION, GENERALLY FOR CONSTRUCTION
PURPOSES. ONLY LARGE DEPOSITS (EARTH DAMS, LARGE CANYON FILLS,
AND SOME ROADWAY AND BRIDGE ABUTMENT FILLS) ARE SHOWN.
YOUNGER ALLUVIUM: UNCONSOLIDATED STREAM DEPOSITS ALONG MAJOR
QyalACTIVE STREAM CHANNELS. CONSISTS OF GRAY, POORLY SORTED GRAVEL,
ISAND, SILT, AND CLAY.
OLDER ALLUVIUM: UNCONSOLIDATED TO MODERATELY CONSOLIDATED STREAM
Qoal DEPOSITS BETWEEN MAJOR ACTIVE STREAM CHANNELS AND ON TERRACES
ABOVE PRESENT VALLEY FLOOR. CONSISTS OF ORANGE - BROWN, POORLY
SORTED GRAVEL, SAND, SILT, AND CLAY.
ACTIVE LANDSLIDE: ACTIVELY OR RECENTLY - MOVING LANDSLIDE WITH
Als FRESH, UNVEGETATED SCARPS AND BROKEN GROUND, UNDRAINED
DEPRESSIONS, AND RECENTLY DISTURBED MAN --MADE FEATURES AND
VEGETATION.
DORMANT LANDSLIDE: CURRENTLY INACTIVE LANDSLIDE WITH WEATHERED
Dls AND OVERGROWN SCARPS, ROUNDED HUMOCKY SURFACE TOPOGRAPHY, AND
UNDISTURBED MAN -MADE FEATURES AND VEGETATION.
OLD LANDSLIDE: LANG- INACTIVE LANDSLIDE WITH SUBDUED, IRREGULAR
Ols TOPOGRAPHY, LOW SLOPE POSITION, WELL-- ESTABLISHED DRAINAGE, AND
UNDISTURBED VEGETATION.
REPAIRED LANDSLIDE: LANDSLIDE WHOSE STABILITY HAS BEEN
ARTIFICIALLY MODIFIED BY 1) REGRADING, 2) REMOVAL OF THE
Rls
LANDSLIDE DEBRIS AND REPLACEMENT WITH ENGINEERED FILL, AND /OR 3)
RETENTION OF THE IN -PLACE LANDSLIDE MASS BY THE INSTALLATION OF
DEEP PIERS, RETAINING WALLS AND /OR A BUTTRESS FILL.
#_. COLLUVIUM: UNCONSOLIDATED TO MODERATELY CONSOLIDATED,
• .
of ORGANIC--RICH, ROCKY SOIL FORMED BY THE DEEP WEATHERING OF BEDROCK
•'. AND ACCUMULATED ON MOST HILLSIDES AND IN SMALL VALLEYS. CHEEPS
SLOWLY DOWNHILL. SHOWN ONLY WHERE INFERRED TO BE THICKER THAN
ABOUT 5 FEET. THE CONTACT BETWEEN COLLUVIUM AND BEDROCK IS
HIGHLY GENERALIZED; THE EXTENT OF COLLUVIAL MATERIAL CAN VARY
FROM THAT SHOWN ON THE MAPS. UNIT INCLUDES THICK RESIDUAL SOIL.
Bedrock Deposits
SANTA CLAR_A FORMATION: RELATIVELY SOFT, CRUDELY STRATIFIED,
QTsc GENERALLY RED -BROWN TO ORANGE -BROWN CONGLOMERATE, SANDSTONE,
SILTSTONE, AND CLAYSTONE. WEAKLY DEFINED FRACTURE SYSTEMS EXIST
IN SOME EXPOSURES. WEATHERS TO TAN TO RED -- BROWN, SANDY SOIL IN
AREAS UNDERLAIN BY CONGLOMERATE AND SANDSTONE AND TO DARK BROWN
TO DARK GRAY CLAYEY SOIL IN AREAS UNDERLAIN BY SILTSTONE AND
CLAYSTONE. THE CLAYEY SOIL TYPICALLY IS MODERATELY TO HIGHLY
EXPANSIVE.
FRANCISCAN COMPLEX: GENERALLY HARD, PERVASIVELY FRACTURED, DARK
KA GRAY SANDSTONE AND SHALE, DARK GREEN GREENSTONE, AND MINOR RED
CHERT AND GRAY LIMESTONE. THE DISTRIBUTION OF INDIVIDUAL ROCK
TYPES COULD NOT BE DETERMINED WITHIN THE SCOPE OF THIS PROJECT OR
SHOWN AT THE SCALE OF THESE MAPS. WEATHERS TO SANDY TO CLAYEY
SOIL THAT TYPICALLY IS MODERATELY TO HIGHLY EXPANSIVE.
MAP SYMBOLS
GEOLOGIC CONTACT BETWEEN DEPOSITS; DASHED WHERE
• APPROXIMATE, DOTTED WHERE CONCEALED BY YOUNGER
DEPOSIT, QUERIED WHERE LOCATION UNCERTAIN.
30
STRIKE AND DIP OF STRATIFICATION.
35
STRIKE AND DIP OF STRATIFICATION FROM OTHER GEOLOGIC
STUDIES.
® HORIZONTAL STRATIFICATION.
i AXIS OF PLUNGING ANTICLINE, LOCATED APPROXIMATELY;
DOTTED WHERE CONCEALED BY YOUNGER DEPOSIT.
AXIS OF PLUNGING SYNCLINE, LOCATED APPROXIMATELY;
-- -7•••••i DOTTED WHERE CONCEALED BY YOUNGER DEPOSIT, QUERIED
WHERE LOCATION UNCERTAIN.
FAULT; DASHED WHERE APPROXIMATE, DOTTED WHERE
? CONCEALED BY YOUNGER DEPOSIT, QUERIED WHERE LOCATION
UNCERTAIN; BARBS ON UPTHROWN SIDE.
FAULT FROM PUBLISHED GEOLOGIC MAPS (REFERENCED);
-- v o o DASHED WHERE APPROXIMATE, DOTTED WHERE CONCEALED BY
YOUNGER DEPOSIT, QUERIED WHERE LOCATION UNCERTAIN;
BARBS ON UPTHROWN SIDE.
00 00 FAULT MAPPED BY CALIFORNIA DEPARTMENT OF WATER
RESOURCES (1975) ON THE BASIS OF DISPLACEMENTS IN
bURIBD STREAM CHANNELS. NO EVIDENCE OF FAULT FOUND AT
SURFACE DURING THIS STUDY.
PHOTOLINEAMENT; ALIGNED TOPOGRAPHIC AND COLOR
ANOMALIES POSSIBLY RELATED TO FAULTING.
45)
LANDSLIDE DEPOSIT; BOUNDARY DASHED WHERE APPROXIMATE,
DOTTED WHERE CONCEALED BY YOUNGER DEPOSIT, QUERIED
WHERE LOCATION UNCERTAIN. ARROWS SHOW DIRECTION OF
_l* //
DOWNSLOPE MOVEMENT. HACHURED LINES INDICATE TOP OF
HEAD SCARP. QUESTION MARK INDICATES EXISTENCE OF
DEPOSIT IS UNCERTAIN.
��) 1011)f DEBRIS FLOW SCARP AND FLOW PATH; ESTIMATED TO BE
YOUNGER THAN 5 YEARS.
SPRING.
EROSION GULLY DEEPER THAN ABOUT 10 FEET.
BASE MAP: U.S. GEOLOGICAL SURVEY TOPOGRAPHIC QUADRANGLES: LOS GATOS
(1953, PHOTOREVISED 1980), CASTLE ROCK RIDGE (19559 PHOTORHVISED 19681
PHOTOINSPECTED 1973), CUPERTINO AND SAN JOSH WEST (19619 PHOTORBVISED
1980).
r±
GEOLOGIC MAPS
OF THE
LOWER SARATOGA HILLSIDE AREA,'�,
SARATOGA, CALIFORNIA
:I, TERRATECH
NOTE TO USERS
f - SHEEY . I
A
DATE DEC_ 1985 DWN BY L9irn,..J CHKD C.v.A APPR
PROJECT I
3595
THESE MAPS SHOW GEOLOGIC DATA OBTAINED BY DETAILED GROUND
RECONNAISSANCE CONDUCTED DURING THE MONTHS OF APRIL, MAY, AND
JUNE OF 1985; INTERPRETATION OF AERIAL PHOTOGRAPHS; AND A REVIEW
OF PUBLISHED AND UNPUBLISHED GEOLOGIC REPORTS AND MAPS. THEY ARK
DESIGNED PRIMARILY FOR USE BY GEOLOGISTS, GEOTECHNICAL ENGINEERS,
AND OTHER PROFESSIONAL EARTH SCIENTISTS. THEY ARE NOT INTENDED
AS A SUBSTITUTE FOR THE DETAILED SITE INVESTIGATIONS THAT ARE
NECESSARY FOR CONSTRUCTION PURPOSES.
WHERE SPECIFIC GEOLOGIC FEATURES ARE SHOWN ON THESE MAPS, FIELD
EVIDENCE WAS FOUND TO SUPPORT THEIR EXISTENCE. ABSENCE OF
APPROPRIATE SYMBOLS (B.G. LANDSLIDES, FAULTS, ETC.) FROM ANY PART
OF THESE MAPS, HOWEVER, MAY NOT BE USED TO PROVE THE ABSENCE OF
THOSE FEATURES IN THE FIELD.
ADDITIONAL EXPLANATION AND DESCRIPTION OF THE GEOLOGIC MATERIALS
SHOWN ON THESE MAPS MAY BE FOUND IN THE REPORT ENTITLED GEOLOGIC
HAZARDS ANALYSIS OF THE LOWER SARATOGA HILLSIDE AREA,__SARATO(AL
CALIFORNIA (DECEMBER 1985)9 BY TERRATECH, INC. A SECOND SET OF
MAPS ENTITLED GROUND MOVEMENT POTENTIAL MAPS OF THE LOWER
SARATOGA HILLSIDE AREAs SARATOGAg CALIFORNIA, WAS PREPARED BY
INTERPRETATION OF THE GEOLOGIC MAPS AND OTHER INFORMATION. THE
GROUND MOVEMENT POTENTIAL MAPS MAY BE OF GREATER INTEREST TO THE
NON-- TECHNICAL USER.
MAP SHEET INDEX
L00 Nu,* v r 5