Lake Lahontan: Geology of southern Carson Desert, Nevada

_ Introduction _ Location. Acknowledgments. ____-_--_--__________--_______ Previous work. -____-_---___________----_---____ Geographic setting. _ ________________________________ Major landforms_____ ___________________________ Carson Desert and adjoining basins. --. ______ Highlands bordering the basinsT __ ___________ Climate _______________________________________ Drainage ______________________________________ Vegetation. _ ___________________________________ Economic geography ____________________________ Tertiary stratigraphy and structure_____________ ______ Stratigr aph y. ___. ______________________________ Basalt of Rainbow Mountain _ ______________ Dacite of Rainbow Mountain. _______________ Eagles House rhyolite _______________________ Truckee formation. _________________________ Bune jug formation. _________________________ Structural features. _ ____________________________ Pre-Truckee faults. _________________________ Faults of post-True kee and early Bune jug age__ Structural features of post-Bunejug pre-Paiute age______ Basin-and-range faults. _ __________. __. _. ___. ___. General features. ___________________________ Faulting in specific areas_____________________ Configuration of the bedrock floor of the basin _____ Quaternary stratigraphy. _ __________________________ Methods of study_____ __________________________ Stratigraphic usage _____________________________ Soils. _________________________________________ Definition and general features _______________ Soil profile. _ _______________________________ Classification. ______________________________ Descriptive terminology _____________________ Great soil groups ___________________________ Pre-Lake Lahontan erosional features _____________ Pre-Lake Lahontan Quaternary stratigraphy _______ Basalt of Rattlesnake Hill ___________________ Pre-Lake Lahontan lacustrine sediments___. ___ Paiute formation ___________________________ Buried pre-Lake Lahontan Quaternary sediments -_-__-__-------____________________ Cocoon soil_______________________________ General features and relations. ___________ Profile characteristics ___________________ Age__ _________________________________ Lahontan Valley group. _________________________ Eetza formation --__-_---______________. __. _ General features. _______________________ Lake gravel. ___________________________ Paga 1 2 2 3 4 4 4 5 5 5 5 7 7 8 10 10 11 12 15 15 15 15 15 15 16 17 17 17 18 19 19 20 20 21 21 22 23 23 23 23 24 24 24 25 28 28 28 28 28 Page Quaternary stratigraphy Continued Lahontan Valley group Continued Eetza formation Continued Shore features______-_-_---____--_-----30 Tufa. ------------------------------31 Intra-Eetza lake recession. _____-_-_-31 Lake sand, silt, and clay ________-_-_-33 Correlation with deposits of Lake Lahontan described by Russell and Antevs _____ 33 Paleontology. ______--------. ----------33 Alluvial gravel and colluvium of Eetza age. ____ 33 Wyemaha formation. ____________----------_ 34 General features. ___. _---___-----------34 Correlation with deposits of Lake Lahontan described by Russell and Antevs _____ 34 Eolian sand. _________-_----_----------34 Alluvial and colluvial gravel and sand. -. 36 Interbedded shallow-lake and subaerial sediments. _ ________------_----_-----36 Subsurface basin sediments_______-_. -__37 Paleontology. __________-. _-----------38 Basaltic tuff of Upsal Hogback___. _--_------38 Churchill soil . --. -. ---------------------38 General relations and distribution_________ 38 Profile characteristics___-_____--_------40 Sehoo formation. ___________---------_-----41 General features. _____________---_-----41 Members. ____________---_------------51 Lower member___________----_----51 Thinolite unit____--_--------------59 Dendritic member. _________________ 61 Upper member_____-_____---------62 Shore features of Sehoo age__________-----_-63 Shorelines of the early Sehoo lake______-_63 Comparative heights of highest Eetza and early Sehoo shorelines at Russel Spit. ___ 64 Lake levels during deposition of the thinolite unit. --. ------------------------65 Shorelines of the middle Sehoo lake; "dentritic terrace"__________-_----------65 Shorelines of the late Sehoo lake________-65 Indian Lakes formation. -. -. -------------68 General features. ____________,---------68 Tongues and age units_________---------68 Alluvium and colluvium above the Lahontan beach________--_-_--_-68 Lower tongue_______-_-_--_-------68 Middle tongue____________-_-_---68 Alluvium of middle Sehoo and Indian Lakes age________--_---_--------69 Alluvium, colluvium, and eolian sand of late Sehoo and Indian Lakes age__ 71 Volcanic-sand complex of Soda Lake. ___-____71