The data for these images is from the Arizona Geologic Society, and the maps
were constructed by grouping related units under more general categories, with
each one focusing on a specific aspect of the Phoenix area geology.
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Geologic Age
(Files with prefix phxgeotime)
This map depicts the geologic age of units in the Phoenix basin. The system of unit designation is relatively self-explanatory - in general, the units are designated by their prefix; for example as Quaternary by a Q prefix, Tertiary by a T prefix, Mesozoic by a K prefix, and Paleozoic or Proterozoic by an X or Y prefix. Under a give geologic age group, the units included are sedimentary, intrusive, volcanic, and metamorphic in nature.
Time is in millions of years. Note: Although the boundary between the Proterozoic and the Archean is about 2500 million years, the units represented in this map generally don't date back more than 1800 million years, so the Proterozoic here is simply limited to the ages of 1800 to 544 mya.
Holocene (<0.01 mya)
Quaternary (<1.8 mya)
Tertiary (66.4-1.8mya)
Mesozoic (245-66.4 mya)
Paleozoic (544-245 mya)
Proterozoic (1800-544 mya)
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Rock Type
(Files with prefix phxgeolith)
This map displays the general lithology of the Phoenix basin, based on both age and type of rock.
Unconsolidated Sediments: Loosely and poorly consolidated recent sediments.
(Units include: Qyc Qy Qtc Qyf Qycr Qyr)
Quaternary Sediments: Holocene and Pleistocene units.
(Units include: water, Ql Qly Qm Qm1 Qm2 Qml Qo Qmo QTs QTl QTr Qye Qlyf Qmlf
Qmyf Qlyr Qmr Q Qy Qt Qe)
Tertiary Sediments: Conglomerates, breccias, sandstones, volcanic-lithic sandstones.
(Units include: Tsy Tsl Tsmy Tsm Tcu Tsu Ts Tx Tsl Txl)
Tertiary Volcanics: Basalt, tuff, and pyroclastic units of mafic and felsic
compostion.
(Units include: Tby Tfy Tv Tsv Tby Tbl Tbs Tru Tr Trt Tt Ta Tf Tba Tta Ttc Tts
Txt Ttn Tb Tvs Tml Trf Tb QTb)
Tertiary Intrusives: This is comprised of Laramide granitoids, and both mafic
and felsic tertiary intrusive units. Dikes, granite (may be muscovite or porphoryitic),
granodiorite, and diorite units may be seen here.
(Units include: TKn Tkga TKd TKg TKgd TKgm TKp TKp TKx Kg Kgd Kd Th Tg Tcb JXg
Ti Tim Td Tdm Tdt)
Paleozoic and Proterozoic Sediments: Limestones, quartzites, and carbonates.
(Units include: Pn MCs Pzs Ya PzYs Xc)
Paleozoic and Proterozoic Igneous: This is comprised of Paleozoic and mid-Proterozoic
diabase and intrusive units, as well as Proterozoic volcanics. Also includes
granite, granitoid, and gabbro units.
(Units include: Yd Yad Yg Ygm YxgYXh Yxd Xd TXg YXg Xg Xa Xqd Xd Xgl Xpg Xf
Xvs)
Metamorphics: Gneiss, schist, and metarhyolite units.
(Units include: Mgn Xr Xp Xpp Xpc Xm Xms Xq Xgf Xt Xmv Xr Xmg Xt)
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Recent Lithology
(Files with prefix phxgeorecentlith)
This map depicts the recent depositional lithology of the Phoenix basin, focusing on the Quaternary (which includes the Holocene (0.01 mya) and Pleistocene (1.8 mya) epochs), as well as the Tertiary. Units older than the Cenozoic (which encompasses these two periods) are simply bedrock.
Holocene: Deposits from modern channels, alluvial fans, terraces, talus cones,
floodplains, and eolian features. Characteristically have poor soil developmenet
(Units include: Qyc Qy Qt Qly Qtc Qycr Qye Qyf Qyr)
Pleistocene: Late to middle Pleistocene deposits consisting of middle and older
alluvium. These units display more that the minimal soil development of the
Holocene units, and often have some carbonate development. Terraces here are
desiccated.
(Units include: Qm Qm1 Qm2 Ql Qlr Qly Qmf Qmlf Qmr)
Older: Older alluvium of a Quaternary to Late Tertiary age.
(Units include: Qo QT QTl QTr)
Undifferentialted: Holocene and Pleistocene alluvium and talus deposits.
(Units include: Q)
Tertiary: Deposits include intrusive and extrusive igneous units, and sedimentary units of all types. (Units include: Everything with a T prefix, excluding Tkd, which is Cretaceous)
Bedrock: This is comprised of all other sedimentary, volcanic, and intrusive
Tertiary, Paleozoic, Proterozoic, and metamorphic units.
(Units include: Everything with no Q or T prefix to the unit)