Bonner County, 117o02’31” 116o48’00” 48o56’45” Idaho Zdt Qm Qm Kgd Kgd Yp Kgdh Kgd Qa Qm Kgd Qm Kgd Qm Yp Yp 0 5 10 miles Qm Kgd Kgd 0 8 16 kilometers Priest Lake Kgd 1:500,000

Kgdh retRi Priest Kgd 116o02’51” Kgdh o Yp 95 Yp Qm 48 30’00” v Kgd 2 Qm e r Qm D

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e Kgd r Qm Yp Qm Yp Kgdh Qm Yp YXm 200 Yp Qm Qm Yp Kgd Sandpoint Qm Tgdd Hope Qm Yp Qm Yp Qm S Kgdh ite o f IcYra 95 e DYc Tgdd YXm Kgd Kgd amYc an Yra 2 Wm Cla d Qm r p nd O Yag Qa Yp k a Pe reil F th le R rielle o o YXm iv Kog Qa rk f M 41 er Yra Ymiu isYmil Yag d Path Yc Ymil so la Floo ula ou nt Flo iss e Cocolalla Yra Ymiu ods M Yr a Yc m Yp Yp h Kgd Ymiu Priest Rv c Qmf Qmf a Lake PendYp Orielle Core Complex t Yra e Qmf Yc D Yra Kgd v YXm R Ktq Tcr Kgdh Qmf t Yc

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Ymil Ymiu Yra 47o53’30” o 116 30’00” Digital Atlas of Idaho, Sept. 2002 http://imnh.isu.edu/digitalatlas Compiled by Reed Lewis, Idaho Geological Survey http://www.idahogeology.org Bonner County The northern and western parts of the Bonner county, west of Sandpoint contain the Priest River metamorphic core complex, containing highly metamorphosed rocks of Proterozoic age. The detachment fault which bounds the core complex runs north along the east side of Priest Lake. Cretaceous intrusive rocks of the Kaniksu batholith (part of the Idaho batholith complex) are found both above and below the detachment fault. Eocene granodiorite intrusive rocks are also found in the center of the metamorphic core. The complex represents recurrent Eocene to Recent uplift. In the eastern part of Bonner County relatively low-grade metasedimentary rocks of the Mesoproterozoic Belt Supergroup make up the mountains east of Lake Pend Oreille and along the Montana border. Southeast of Lake Pend Oreille is a small area underlain by Cambrian limestones similar to those mined for lead, zinc and gold near Metaline Washington. The Lake Missoula flood broke out of the Clark Fork Canyon in the eastern Bonner County about 16,000 years ago, with the ice dam spanning the eastern bays of Lake Pend Oreille. The flood broke out to the south and west of Lake Pend Oreille as it flowed into Rathdrum Prairie and the Spokane River Written by P.K. Link, 9/02

Descripton of Units for Bonner County Idaho

Qa Quaternary alluvial deposits Qm Quaternary moraine (unsorted boulders, cobbles and sand) and glaciofluvial outwash (bedded stream deposits formed from streams draining active glacial ice). Qmf Missoula Flood deposits; boulder bars and gravel along route of Missoula flood on Rathdrum Prairie south and west of Lake Pend Oreille. Ts Tertiary sedimentary rocks, undifferentiated. Includes Oligocene and Eocene sedimentary rocks in east-central Idaho (Paleogene basins of Janecke). In northern and western Idaho this unit contains Miocene lake and stream deposits formed adjacent to and above the Columbia River and Weiser basalts, which formed dams in stream canyons. Tcr Miocene basalt (Columbia River Basalt Group); flood basalt, extensively exposed in western Idaho; fed by fissures, many of which are near the Idaho-Oregon border. Flowed eastward up valleys cut into the Idaho mountains. Tgdd Eocene granodiorite and dacite porphyry intrusive, also includes diorite and, in northern Idaho, minor granitic rock; intermediate phase of Challis magmatic event (50 to 46 Ma). Summit Creek stock. Kgd Cretaceous granitic rocks of the 2 mica suite. Idaho batholith and related plutons; granite and granodiorite that contains both muscovite and biotite. Sodium (Na) rich. Intruded between 80 and 65 Ma. Kgdh Cretaceous granitic rocks of the hornblene-biotite suite; granite, granodiorite and megacrystic granodiorite. Potassium (K) rich. Age about 80 to 90 Ma. Zdt Deer Trail Group, quartzite, siltstone, conglomerate. Yag Mesoproterozoic augen gneiss and porphyritic granite; near Shoup on the Main Salmon River age is 1370 Ma. Ymiu Upper Missoula Group. Includes Swauger Quartzite, Lawson Creek Formation in Lemhi Range, and Striped Peak and Libby formations In northern Idaho. Ymil Lower Missoula Group. Includes Gunsight Formation in Lemhi Range and upper Wallace Formation (equivalent to Snowslip and Shepard formations) in northern Idaho. Yc Piegan Group or Middle Belt carbonate, Apple Creek Formation [includes lower and middle Wallace Formation in northern Idaho and Apple Creek Formation and argillaceous quartzite (including rocks at Cobalt) near Salmon]. Yra Ravalli Group, sandstone (quartzite) and siltite, includes Big Creek Formation and lower part of Lemhi Group in Lemhi Range and Salmon River Mountains, and Burke, Revett and St. Regis formations in northern Idaho. Yp Prichard Formation (Lower Belt), dark fine-grained siltstone and sandstone, calcareous intervals in Boehl's Butte area. Yqra Quartzite and schist of the Ravalli Group. Ysp Schist, gneiss and minor quartzite of the Prichard Formation.

Metamorphic Rocks of Uncertain Affinity, pre- and/or syn Belt Supergroup

YXm High-grade metamorphic rocks (schist, gneiss, quartzite, calc-silicate rocks); includes Elk City metamorphic sequence and related rocks, Syringa metamorphic sequence, and Priest River metamorphic complex.

Paleoproterozoic and Achaean Metamorphic Rocks

Wm Archean gneiss and schist, Albion Range, and Priest River complex west of Sandpoint.

Symbols

Geologic unit contacts with unit Overturned anticline: trace of axial Yp designation. plane.

Normal fault: certain; dashed where Overturnedsyncline: trace of axial approximately located; dotted where plane. concealed. Location of ISU Rockwalk rock Thrust fault: certain; dashed where from each county. approximately located; dotted where concealed. Cities Detachment fault: certain; dashed Feature location where approximately located; dotted where concealed. Roads Anticline: trace of axial plane: large Interstate Route arrow indicates direction of plunge. 15 U.S. Route Syncline: trace of axial plane: large 95 arrow indicates direction of plunge. 1 State route