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Geologic map of the North Lake Tahoe - Donner Pass Region



Geologic map of the North Lake Tahoe - Donner Pass Region, Northern Sierra Nevada, California


California Geological Survey, Map Sheet 60, 1:48,000 scale

Compiled by: Arthur Gibbs Sylvester, William S. Wise, Jordan T. Hastings, and Lorre A. Moyer

2012

Digital Preparation by: Carlos I. Gutierrez and Barbara Wanish

DESCRIPTION OF MAP UNITS
Alluvium and related deposits; glacial deposits 

Recent Alluvium 
Colluvium 

Lacustrine deposits 
Sand dunes
Older alluvium
Fan deposits
Colluvium and glacial drift, undivided
Landslide
Talus
Older lacustrine deposits
Tioga glacial deposits 
Till
Outwash deposits
Ponded deposits
Tahoe glacial deposits 
Till
Outwash deposits
Donner Lake glacial deposits 
Drift
Outwash deposits
 
Truckee River Formation 
Cinder cone deposits
Trachyandesite of Tahoe City
Tahoe City basalt
Trachybasaltic andesite flow of Deer Creek
Olivine basalt of Lake Forest
Juniper Flat alluvium
Prosser Creek alluvium
Hirschdale basalt
Trachyandesite and dacite flows and domes of Dry Lake
Unit 4, youngest
Unit 3
Unit 2
Unit 1, oldest
 
Bald Mountain basalt
Olivine basalt flows, undivided
Olivine basalt flows of Page Meadow
Olivine basalt flows of Polaris
Olivine basalt flows of Burton Creek
Fluvial sand and gravel of Cabin Creek
Olivine basalt of Alder Hill
Trachyandesite flows of Agate Bay
Volcaniclastic rocks of Skylandia
Trachyandesite flows of Cedar Flat
Trachyandesitic plug
Fir Crags gravel
 
Mehrten Formation 
Squaw Peak member 
Basalt flows
Basaltic andesite flows
Andesitic intrusions, plugs, and dikes
Biotite-hornblende andesite domes and flows
Biotite-hornblende andesite intrusions
Block and lapilli tuff breccia of Mt. Disney
Stratified volcaniclastic deposits
Volcaniclastic deposits, undivided
Pyroxene andesite flows
Hornblende andesite flows
Martis Peak member 
Aphyric or microporphyritic andesite lava flows
Andesitic intrusions, plugs, and dikes
Andesitic volcaniclastic deposits
Basaltic andesite flows
Pyroxene andesite flows
Hornblende andesite flows
Hornblende andesite intrusion
Mt. Lincon member 
Basalt lava flows
Basaltic tephra
Intrusive plugs and dikes
Andesite lava flows, undivided
Andesite lava flows, aphyric
Hornblende andesite lava flows
Hornblende andesite intrusion
Pyroxene andesite flows
Basaltic andesite flows
Diabase intrusion
Fluvial strata intercalated with Tlp and Tllt
Undivided
Youngest
Intermediate
Oldest
 
Volcaniclastic rocks, undivided
Lapilli tuff breccia
 
Valley Springs Formation 
Rhyolite tuff, undivided
Nine Hill Tuff
Rhyolite tuff
Mickey Pass Tuff
Tuff of Campbell Creek
Tuff E
Rhyolite tuff
Tuff of Sutcliffe
Rhyolite tuff of Rattlesnake Canyon
 
Granitic Rocks 
Hornblende-biotite granodiorite of Summit Lake
Hornblende-biotite granodiorite with K-spar megacrysts diorite
Tonalite of Lake Mary
Granodiorite
Hornblende-biotite granodiorite, undivided
Quartz monzonite, undivided
 
Lake Tahoe Sequence of Harwood (1992) 
Ellis Peak Formation 
Quartz arenite
Blackwood Formation 
Sandy limestone and pelitic hornfels
Onion Creek Formation 
Marble and calc-silicate hornfels
Serena Creek Formation 
Biotite schist
Picayune Valley Formation 
Chert and quartz-rich conglomerate, quartzose sandstone, and pelitic hornfels.
 
Gneiss of unknown affinity
MAP SYMBOLS
Contact between map units - Solid where accurately located, dashed where approximately located; short dash where inferred; dotted where concealed; queried where uncertain.
Contact separating individual lava flows within the same map unit.
Fault - Solid where accurately located, dashed where approximately located; short dash where inferred; dotted where concealed; queried where uncertain. Ball and bar on downdropped block.
Landslide scarp
Moraine crestline, approximately located
Dike
Dike intruding fault
Hydrothermal alteration; boundary approximately located.
Inclined Bedding
Horizontal bedding
Inclined foliation
Vertical foliation
Strike and dip of inclined cleavage
Location and number of radiometrically dated rock sample. Age data are presented in Tables 1 and 2 in the accompanying pamphlet.

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