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<br /> DESCRIPTION OF MAP UNITS \ ;--v -
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<br /> Qs J Sand dunes(Holocene) Windblown sand and dune sand
<br /> r Qo Flood-basin deposits (Holocene) Clay, silt, and some sand;near Stockton \
<br /> consist of muck,peat,and other organic sods. In places may include part
<br /> of the Modesto Formation(Pleistocene) -- -
<br /> �tt I'r=
<br /> River deposits (Holocene) Gravel, sand, silt, and minor amounts of clay; PTs SP
<br /> deposited along channels,flood plains,and natural levees of main streams.
<br /> r In places may include part of Modesto Formation(Pleistocene) v
<br /> QTI Laeustrina and marsh deposits (Pliocene to Holocene) Clay,silt,and some
<br /> sand; in subsurface include three widespread clays- A clay (Pleistocene
<br /> and Holocene?);C clay(Pleistocene);and modified E clay(Pleistocene). Geolo Ic Ma from KWPa e,1986,USGS Professional Pa er 1401-C.
<br /> includes Corcoran Clay Member of Tulare and Turlock Lake Formations 9 p 9 p
<br /> CTc Continental rocks and deposits(Miocene to Holocene) Heterogeneous mix of
<br /> am generally poorly sorted clay,silt,sand,and gravel:some beds of claystone,
<br /> siltstone, sandstone, and conglomerate. Include some informal units:
<br /> younger alluvium (Holocene),older alluvium(Pleistocene and Holocene?) A GELOGIC MAP OF THE
<br /> and continental deposits (Pliocene and Pleistocene);three formations of
<br /> Pleistocene age: Modesto,Riverbank,and Turlock Lake;Tulare Forma-
<br /> tion (Pliocene and Pleistocene) on western side of valley, Laguna Far- SAN JOAQUIN VALLEY
<br /> motion(Pliocene)on eastern side,and Kerr.River Formation(Miocene to
<br /> am Pleistocene?)on southeastern part
<br /> Volcanic rocks and deposits (Miocene and Pliocene) Massive tuff with large
<br /> 4ragments of vesicular basalt northwest of Tracy; tuff, and volcanic
<br /> breccia at south end of valley
<br /> F__1 Continental rocks and deposits(Miocene and Pliocene) Gravel,sand,silt,clay.
<br /> Ifte. conglomerate, sandstone. siltstone,and claystone, contain andesitic
<br /> material. Principally Mehrten Formation (Miocene and Plionene) on
<br /> eastern side of valley:inrlude continental equivalents of Etchegbin For-
<br /> mation (Miocene and Pliocene) on western side of valley,and Chanac
<br /> Formation(Miocene)on southern part
<br /> Continental and marine rocks and deposits (Miocene and Pliocene) Gravel,
<br /> a� sand, silt, clay, silty sandstone,and siltstone. Include continental and Scale:1.500,00
<br /> marine equivalents of San Joaquin Formation (Pliocene) and Etchegoin
<br /> Formation(Miocene and Pliocene) 1 in=8 mi
<br /> ®Marine rocks and deposits(Eocene,Oligocene,Miocene,and Pliocene) Sand,
<br /> clay,silt,sandstone, shale, mudstone,and siltstone. On western side of
<br /> valley include the San Joaquin and Etchegoin Formations, Temblor
<br /> Formation (Oligocene and Miocene) and Kreyenhagen Formation
<br /> (Eocene). On southeastern side include the Santa Margarita Formation of
<br /> various authors,the Round Mountain Silt,the Olcese Sand,the Freeman
<br /> Silt,and the Jewett Sand(Including the Pyramid Hill Sand Member) (all
<br /> Miocene),and the Vedder Sand(Oligocene)
<br /> Tcmo ContinquZ rocks and deposits(Oligocene and Miocene) Gravel,conglomerate,
<br /> e. sand,tuffaceous sand,clay.and sandy clay;contain rhyolitic material on
<br /> eastern side of valley. Principally Valley Springs Formation(Oligocene
<br /> and Miocene)on eastern side of valley;unnamed fanglomerates(Miocene)
<br /> and Sena Gravel(Miocene)in the southern part
<br /> Continental rocks and deposits(Eocene to Miocene) Conglomerate,sandstone,
<br /> consolidated fanglomerate,claystone,tuff and tuff breccia:near Fresno
<br /> a� consist of tuffaceous sand and gravel. Near Bakersfield include the
<br /> Bealville Fanglomerats (Oligocene and Miocene) and the Walker For-
<br /> mation(Eocene to Miocene)
<br /> EgoContinental rocks and deposits(Eocene) Conglomerate and sandstone:along
<br /> eastern side of valley contain anauxite. Principally Ione Formation
<br /> (Eocene)on eastern side of valley
<br /> Unconformity E R
<br /> j,o so
<br /> Marine rocks (Pro Tertiary) Sandstone,shale,siltstone,and some limestone. r '�
<br /> chiefly on western side of valley; in places contain abundant secondary NEIL O.ANDERSON 8 ASSOC., INC
<br /> gypsum. Include Moreno Formation (Cretaceous and Paleocene) and > r^
<br /> Panoche Formation(Cretaceous) GEOTECHNICAL SERVICES-ENGINEERING LABORATORIES Z 4a
<br /> 22 H.—Wn Ln.Lodi,CA 95240 O
<br /> ®Granitic rocks(Pre-Tertiary) Chiefly granitic rocks on eastern side of valley,in 12091362-3)01 7 \�
<br /> places consists of mafic intrusive rocks d S O O
<br /> Metamorphic rocks (Pre-Tertiary) Matasedimentary,metavolcanic and other pIa1,C 6
<br /> metamorphic rocks on?astern side of valley
<br /> a.
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