Scientific Investigations Map 2927 U.S. Department of the Interior Sheet 2 of 2 U.S. Geological Survey Pamphlet and CD-ROM accompany map 155° 115° 225° 190° L C M B A B A M 121°45’ 121°37’30” 121°30’ 121°22’30” 41°30’ 41°30’

SECTOR LOCATION MAP CORRELATION OF MAP UNITS Shaded relief map showing Medicine Lake volcano (magenta outline) divided into 13 radial sectors [Sector letters A-M indicate location of unit on map: see "Sector Location Map" for approximate azimuths of sector boundaries; on map, ends of sector boundaries are indicated by short lines adjacent to map area. (A-M). Approximate azimuths of sector boundaries are shown at end of each sector boundary line Units other than surficial deposits are arranged chronologically within each sector column; units present in more than one sector are shown in multiple sector columns; dashed lines at top and (or) bottom of unit (dot near center of Medicine Lake is starting point for each azimuthal direction). Sector letters indicate that upper and (or) lower chronologic position(s) of unit is (are) poorly constrained. Time division boundaries (dotted lines) are from Richmond and Fullerton (1986); interim ages (5, 13, 100, 180, 300, and indicate location of unit on map in “List of Map Units” and correspond to columns in “Correlation of Map Units.” 500 ka), which are approximate boundaries of five eruptive stages discussed in text (in accompanying pamphlet), are shown as thicker gray lines for reference. Argon-dated units are shown with asterisk (*); see BURNT "Description of Map Units" and table 1 (both in pamphlet) for unit ages. Note that, in sector columns J and K, units rmh, aib, and bmc are shown joined together because their argon ages overlap, but these units LAVA 330° 355° 10° 25° actually do not overlap in field and so their relative ages are unknown] FLOW 121°45' 121°15'

41°52'30" SURFICIAL DEPOSITS VOLCANIC ROCKS g L M Sector: A BCDEFGHI J K LM 115° 48° rgm rgm rlg* rlg rlg rlg p mpp mpp mcf mcf mcf H I rh rh rh G abl bbr abl Holocene J byb dpc dpc HARRIS dm dm dm dm 5 ka MOUNTAIN 11.5 ka bv5 bvc bvc bvc

C F K bgc bgc mgf btm bdh bdh brf 295° 13 ka B 75° bwc bwc bup bec bma mna 225° t DERA R bgd bgd bc AL IM C

ms bmc* bmc* bmc* rmh* aib* bmc* rmh* aib* bmc* aib* E bwh bwh buc Medicine Lake L msm bci 260° D mts asb* PORCUPINE BUTTE bpa Sheet 1 byb* beb byb* byb* C 41°30' 245° Sheet 2 bl* bl* bl* bl* bl*

bt bt Late Pleistocene B M 115° bls* drs* drs* 100 ka anr* anr* anr* anr* anr* anr* anr* A bu 225° l asm bsc asm rng* asr* asr* asr* asr* asr* asr*

bnf bsl bsl bsl aac* aac* AREA OF MAP

brh brh awl awl bac bac bac bac

mnm mnm mnm as bpw as mel mhi mhi bts bts men* men* bnp bnp mfh* mfh* m1 132 ka 121° 45’ 41°15' bdp 121°45' awb awb ama bng bng bnb 190° 41°22’30” 41°22’30” muc a1 aug aug m16 awf blh* Base from U.S. Geological Survey 1:24,000-scale quadrangles: Captain Jacks Stronghold, Red 155° aut aut m2 m2 Rock Lakes, 1985 (provisional eds.); Bonita Butte, Copic, Garner Mountain, Little Glass Mountain, g bdb* bdb* bnw Schonchin Butte, Sharp Mountain, Tulelake, 1988 (provisional eds.); Border Mountain, Hambone, Horse Peak, Snag Hill, 1990 (provisional eds.); Caldwell Butte, Egg Lake, Hollenbeck, Kephart, Medicine Lake, Mount Dome, Perez, Porcupine Butte, The Panhandle, West of Kephart, White msc msc Horse, 1993; East of Pondosa, Indian Spring Mountain, Timbered Crater, 1995 121° anh anh 22’ Lambert Conformal Conic projection 30” B bcb b4 A bei msp* msp* bwd adh* b9 121° mes mrs 190° 30’ aeg aeg aeg aeg btw ds* M b5 bco A ay mug* mug* mug* mug* m10 b6 bse 121° 155° bpb bpb m12 m12 a3 m9 m14 37’ 30”

mdp mdp a5 a5 m7 m11 m11 bdc m5 bdc acc mwg mwc bcu m3 mhm mhm bgf mni bph bph

asn

bnr bwl 15° SCALE 1:50 000 Geology by J.M. Donnelly-Nolan 1979-1992 180 ka dta* dta* dta* dta* dta* dta* dta* dta* dta* 1 1/2 0 1 2 3 4 MILES Digital database and cartography by D.W. Ramsey, T.J. Felger, E. Lougee, and P. Bruggman 3000 0 3000 6000 9000 12000 15000 18000 21000 FEET dls* dls* bst bst QUATERNARY CALIF. Edited by Taryn A. Lindquist; digital cartographic production 1 .5 0 1 2 3 4 5 KILOMETERS by Kathryn Nimz bsp TRUE NORTH mrc mrc dec* dec* dec* mtc deg* MAGNETIC NORTH Manuscript approved for publication June 20, 2006 APPROXIMATE MEAN CONTOUR INTERVALS 5, 10, 20, AND 40 FEET MAP LOCATION DECLINATION, 2010 SUPPLEMENTARY CONTOUR INTERVALS 5, 10, AND 20 FEET mbp mbp mbp mc mnd a2 awh awh awh mph mph asc asc a4 beg b12 bsh a9 dac mwd a8 m19 m19 a7 LIST OF MAP UNITS b14 a6 [Map units are divided into surficial deposits, volcanic rocks, and units older than Medicine Lake volcano. Surficial deposit units are listed alphabetically by unit symbol. Volcanic rock units are subdivided into compositional b13 b15 categories, as indicated by first letter of unit symbol (b, basalt; m, basaltic andesite; a, andesite; d, dacite; r, rhyolite); within these categories, units are listed alphabetically by unit symbol; isolated cinder cones are shown with MAYFIELD anl anl anl stipple pattern; units that were erupted since last glaciation are shown with random "v" pattern. Units older than Medicine Lake volcano are subdivided into surficial deposits and volcanic rocks; within these categories, units are b11 msn m18 bss listed alphabetically by unit symbol. Sector letters indicate location of unit on map; see "Sector Location Map" for approximate azimuths of sector boudaries; see "Correlation of Map Units" for relative ages of units within each mtr mtr b17 sector. Argon-dated units are shown with asterisk (*); see "Description of Map Units" (in accompanying pamphlet) for complete unit descriptions and unit ages; see also, table 1 (in pamphlet) for argon ages]

bh

SECTOR(S) FAULT mlc SURFICIAL DEPOSITS bnb Basalt north of Burnt Lava Flow (middle Pleistocene) M m17 Basaltic andesite cone northeast of Cinder Cone (middle Pleistocene) B a6 Andesite cone southwest of Fourmile Hill (middle Pleistocene) F rh Rhyolite of “Hoffman flows” (Holocene) J, K, L b10 b10 b8 Middle Pleistocene g Gravel (Pleistocene) All except D, H, K bnf Basalt northeast of Fourmile Hill (late Pleistocene) H m18 Basaltic andesite cone south of Paint Pot Crater (middle Pleistocene) C a7 Andesite cone west of Crater Glass Flow (middle Pleistocene) F rlg Rhyolite of Little Glass Mountain (Holocene) C, D, E, F bet mlh b2 l Lake deposits (Holocene and Pleistocene) All bng Basalt northeast of Glass Mountain (middle? Pleistocene) J, K m19 Basaltic andesite of Six Shooter Butte (middle Pleistocene) A, B a8 Andesite cone south of Little Mount Hoffman (middle Pleistocene) D rmh* Rhyolite of Mount Hoffman (late Pleistocene) J, K dwm b3 p Pumice (Holocene) bel D, E, F, J, K, L bnp Basalt near Paint Pot Crater (late? Pleistocene) C, D mbp Basaltic andesite of Badger Peak (middle Pleistocene) E, F, G a9 Andesite cone southwest of Little Mount Hoffman (middle Pleistocene) D rng* Rhyolite northwest of Glass Mountain (late Pleistocene) K awm awm t Glacial till (late Pleistocene) A, B, C, E, F, J, L, M bnr Basalt north of railroad (middle Pleistocene) A mc Basaltic andesite south and southwest of Caldwell Butte (middle Pleistocene) J aac* Andesite of Alcohol Crater (late Pleistocene) L, M rse* Rhyolite at southeast edge of Callahan Flow (middle Pleistocene) H, I rcg dsk* b1 VOLCANIC ROCKS bnw Basalt north of Whitney Butte (middle Pleistocene) H mcf Basaltic andesite of Callahan Flow (Holocene) G, H, I abl Andesite of Burnt Lava Flow (Holocene) A, M rsl* Rhyolite south of Little Sand Butte (middle Pleistocene) K bp* mnl* mnl* BASALT bp* Basalt of Prisoners Rock (middle Pleistocene) J mdp Basaltic andesite of Doe Peak (middle Pleistocene) B, C acc Andesite of Cinder Cone (middle Pleistocene) B rwc* Rhyolite west of Callahan Flow (middle Pleistocene) G

b7 arr b1 Basalt of Hardin Butte (middle Pleistocene) I bpa Basalt of The Panhandle (late Pleistocene) J mel Basaltic andesite east of Little Glass Mountain (late? Pleistocene) D adh* Andesite near Devils Homestead (middle Pleistocene) H UNITS OLDER THAN MEDICINE LAKE VOLCANO m17 mj b16 b2 Basalt cone at northeast edge of Sharp Mountain (middle Pleistocene) F bea bea bpb Basalt of Porcupine Butte and Timber Hill (middle Pleistocene) A, B men* Basaltic andesite of Eagle Nest Butte (late Pleistocene) H, I aeg Andesite east of Grasshopper Flat (middle Pleistocene) B, C, D, E SURFICIAL DEPOSITS mrr* mrr* m4 b3 Basalt cone at east edge of Sharp Mountain (middle Pleistocene) F bph Basalt of Papoose Hill (middle Pleistocene) A, B mes Basaltic andesite of East Sand Butte (middle? Pleistocene) K ael Andesite east of Lost Spring (middle Pleistocene) C og Older gravel deposits (middle and early Pleistocene) F, G 41°15’ 41°15’ m6 b4 Basalt of Caldwell Butte (middle? Pleistocene) J bpw Basalt near Pumice Stone Well (late Pleistocene) E mfh* Basaltic andesite of Fourmile Hill (late or middle Pleistocene) F, G aes* Andesite east of Six Shooter Pass (middle Pleistocene) F, G ol Older lake sediments (middle and early Pleistocene) G atm* atm* b5 Basalt cone southeast of Mammoth Crater (middle? Pleistocene) I VOLCANIC ROCKS m8 brf Basalt of ribbon flows (late Pleistocene) M mgf Basaltic andesite east of Grasshopper Flat (late Pleistocene) C aet Andesite east of Typhoon Mesa (middle Pleistocene) D m15 mtl mtl oag Older andesite of Garner Mountain (middle Pleistocene) E b6 Basalt cone at southeast end of Hidden Valley (middle Pleistocene) I brh Basalt of Red Hill (late Pleistocene) B, C mhi Basaltic andesite of Hippo Butte (late Pleistocene) H, I afr Andesite of Fisk Ridge (middle Pleistocene) C, D afr afr oap* Older andesite of Pumice Stone Mountain (middle or early Pleistocene) D, E, F b7 Basalt cone southwest of Bonita Butte (middle Pleistocene) F bsc Basalt southwest of Cinder Butte (late Pleistocene) G mhm Basaltic andesite adjacent to Harris Mountain (middle Pleistocene) B, C aib* Andesite of Indian Butte (late Pleistocene) J, K, L mws mws ob Older basalt (middle and early Pleistocene) B, F, G, H, J, K, L m13 b8 Basalt cone east of Cinder Butte (middle Pleistocene) H bse Basalt southwest of East Sand Butte (middle Pleistocene) K mj Basaltic andesite of Juniper Butte (middle Pleistocene) J ama Andesite southwest of Mammoth Crater (middle Pleistocene) I mrl obc Older basalt of Casuse Mountain (middle or early Pleistocene) J b9 Basalt cone north of Aspen Crater (middle Pleistocene) J bsh Basalt of Saddle Hills (middle Pleistocene) A mlc Basaltic andesite of Lava Crack Spring (middle Pleistocene) B anh Andesite northeast of Mount Hoffman (middle Pleistocene) J, K 300 ka ael mwr* mwr* aes* aes* obd Older basalt of Dry Lake (middle Pleistocene) B b10 Basalt cone southwest of Dock Well (middle Pleistocene) E, F bsl Basalt south of Little Glass Mountain (late Pleistocene) B, C, D mlh Basaltic andesite of Little Mount Hoffman (middle Pleistocene) E anl Andesite north of Little Glass Mountain (middle Pleistocene) E, F, G msr mtf rsl* rec* obg Older basalt of Gillem Bluff (Pliocene) H b11 Basalt cone northeast of Six Shooter Butte (middle Pleistocene) A bsp Basalt of Shotgun Peak (middle Pleistocene) M mna Basaltic andesite northeast of Aspen Crater (late Pleistocene) J anr* Andesite of north rim (late Pleistocene) D, E, F, G, H, I, J bsr rse* rse* obp Older basalt on west side of Gillem Fault (early Pleistocene) H b12 Basalt cone northeast of Doe Peak (middle Pleistocene) C bsr Basalt southwest of Red Cap Mountain (middle Pleistocene) D mnd Basaltic andesite northeast of Doe Peak (middle Pleistocene) C arr Andesite of old railroad (middle Pleistocene) G aet rwc* obu Older basalt under Black Mountain (early Pleistocene) L, M b13 Basalt cone east of Six Shooter Butte (middle Pleistocene) A bss Basalt south of Squaw Peak (middle Pleistocene) D mni Basaltic andesite north of Indian Butte (middle Pleistocene) J as Andesite of south flank (late? Pleistocene) A, M rgf* rgf* rgf* mnp mnp obw Older basalt of Garner Mountain (middle Pleistocene) E, F b14 Basalt cone east of Doe Peak (middle Pleistocene) C bst Basalt southwest of Tickner Cave (middle Pleistocene) I, J mnl* Basaltic andesite north of Lookout Butte (middle Pleistocene) F, G asb* Andesite of Schonchin Butte (late Pleistocene) I rcb* b15 Basalt cone south of High Hole Crater (middle Pleistocene) M odh* Older dacite of Harris Mountain (Pliocene) B, C bug* bug* bhp* bt Basalt of Tionesta (late Pleistocene) K, L mnm Basaltic andesite north of Medicine Lake (late Pleistocene) G, H, I asc Andesite from cone at southeast edge of Callahan Flow (middle Pleistocene) G, H reg* reg* b16 Basalt of Snell Butte (middle Pleistocene) M 121° ods Older dacite of Squaw Peak (early? Pleistocene) D, E bhi btm Basalt of tree molds (late Pleistocene) G 30’ mnp Basaltic andesite northwest of Paint Pot Crater (middle Pleistocene) D, E asm Andesite south of Mammoth Crater (late Pleistocene) I, J om* Older basaltic andesite of Bonita Butte (early Pleistocene) G b17 Basalt of Round Mountain (middle Pleistocene) M bts Basalt of Three Sisters (late? Pleistocene) F, G mph Basaltic andesite of Powder Hill (middle Pleistocene) A, B asn Andesite of Snag Hill (middle Pleistocene) B UNITS OLDER THAN MEDICINE LAKE VOLCANO omb* Older basaltic andesite of Black Mountain (middle Pleistocene) L, M bac Basalt of Aspen Crater (late Pleistocene) I, J, K, L btw Basalt of Twin Sister (middle Pleistocene) J mpp Basaltic andesite of Paint Pot Crater (Holocene) C, D asr* Andesite of south rim (late Pleistocene) A, B, C, D, E, M 500 ka obw obw omf Older basaltic andesite of Fisk Ridge (middle Pleistocene) D obd bbr Basalt of Black Crater and Ross Chimneys (Holocene) I bu Basalt near Undertakers Camp (late Pleistocene) M mrc Basaltic andesite of Red Cap Mountain (middle Pleistocene) D, E atm* Andesite of Typhoon Mesa (middle Pleistocene) D, E opt opt 121° omf oag omb* omb* bc Basalt of The Castles (late Pleistocene) 30’ omg Older basaltic andesite of Gillem Bluff (Pliocene) H oml I buc Basalt under Callahan Flow (late Pleistocene) G mrl Basaltic andesite of road to Lost Spring (middle Pleistocene) C aug Andesite under Glass Mountain (middle Pleistocene) K, L 788 ka obc oap* oap* oap* ob* ob bcb Basalt of Canby Bay (middle Pleistocene) I oml Older basaltic andesite of Lost Iron Well (middle or early Pleistocene) B ob bug* Basalt under Giant Crater lava field (middle Pleistocene) A, B mrr* Basaltic andesite of railroad (middle Pleistocene) A, B aut Andesite under Three Sisters (middle Pleistocene) F, G obu obu orr* orr* orr* ord* obp bci Basalt of Caldwell Ice Caves (late Pleistocene) J omt* Older basaltic andesite of Timber Mountain (late Pliocene) K, L ob ob bup Basalt under Paint Pot Crater flow (late Pleistocene) C mrs Basaltic andesite of Red Shale Butte (middle Pleistocene) L awb Andesite of Whitney Butte (middle Pleistocene) G, H og ol ods ods bco Basalt of Cougar Butte (middle Pleistocene) K omw Older basaltic andesite in western Lava Beds National Monument (Pliocene) H otb* otb* otb* ob bv5 Basalt of “vent 5” (late Pleistocene) B ms Basaltic andesite of Stud Hill (late Pleistocene) A awf Andesite west of Fleener Chimneys (middle Pleistocene) H bcu Basalt of unnamed crater (middle Pleistocene) I opt Older palagonite tuff (middle? Pleistocene) G, H ob ob bvc Basalt of Valentine Cave (late Pleistocene) I, J, K msc Basaltic andesite of Semi Crater (middle Pleistocene) H, I awh Andesite west of Little Mount Hoffman (middle Pleistocene) D, E, F Early Pleistocene bdb* Basalt of Damons Butte (middle Pleistocene) K, L ord* Older rhyolite near Dock Well (early Pleistocene) F om* bwc Basalt of Water Caves (late Pleistocene) A, B msm Basaltic andesite south of Mammoth Crater (late Pleistocene) I awl Andesite west and north of Little Glass Mountain (late Pleistocene) D, E 1.65 Ma orr* Older rhyolite of Red Cap Mountain (early Pleistocene) C, D, E bdc Basalt of Deep Crater (middle Pleistocene) A, M bwd Basalt west of Doe Peak (middle Pleistocene) C msn Basaltic andesite southwest of Snag Hill (middle Pleistocene) B awm Andesite west of Medicine Lake (middle Pleistocene) E, F omt* omt* bdh otb* Older tuff of Box Canyon (early Pleistocene) F, G, H otg* Basalt of Devils Homestead (late Pleistocene) H, I bwh Basalt west of Mount Hoffman (late Pleistocene) J, K msp* Basaltic andesite east and northeast of Shotgun Peak (middle Pleistocene) L, M ay Andesite under basalt of Yellowjacket Butte (middle Pleistocene) A bdp Basalt of Doe Peak (middle Pleistocene) otg* Older tuff of Gillem Bluff (Pliocene) H omg C bwl Basalt west of Lava Crack Spring (middle Pleistocene) B msr Basaltic andesite southwest of Red Cap Mountain (middle Pleistocene) D DACITE bea obg Basalt east of Antelope Well (middle Pleistocene) F, G byb* Basalt of Yellowjacket Butte (late Pleistocene) A, L, M mtc Basaltic andesite near Tickner Cave (middle Pleistocene) J dac Dacite in Aspen Crater (middle Pleistocene) J Pliocene

TERTIARY beb Basalt east of Big Sand Butte (late Pleistocene) Contact omw K BASALTIC ANDESITE mtf Basaltic andesite of Tamarack Flat (middle Pleistocene) E dec* Dacite east of Callahan Flow (middle Pleistocene) G, H, I Basaltic andesite spatter vent west-northwest of Bat Butte (late or middle H Internal contact bec Basalt east of Cinder Butte (late Pleistocene) H m1 mtl Basaltic andesite of Tamarack Lake (middle Pleistocene) D, E deg* Dacite east of Glass Mountain (middle Pleistocene) L odh* odh* Pleistocene) Sector: ABCDEFGHI J K LM beg Basalt east of Glass Mountain (middle Pleistocene) L m2 Basaltic andesite of Crescent Butte (middle Pleistocene) I, J mtr Basaltic andesite of “Tennant Road” (middle Pleistocene) E, F dls* Dacite east of Lost Spring (middle Pleistocene) C, D Fault—Solid where accurately located; dotted where concealed. Bar and ball on downdropped block. Some faults are cracks that have no offset bei Basalt east of Indian Butte (middle Pleistocene) K m3 Basaltic andesite of Big Sand Butte (middle Pleistocene) K mts Basaltic andesite of Three Sisters (late? Pleistocene) J dm Dacite of Medicine Lake Glass Flow (Holocene) G, H, I, J Lava tube 121°30' bel Basalt east of Lost Iron Well (middle Pleistocene) B m4 Basaltic andesite cone southwest of Cinder Butte (middle Pleistocene) G muc Basaltic andesite under Callahan Flow (middle Pleistocene) G dpc Dacite of pit craters (Holocene) L, M EXPLANATION Lava Beds National Monument boundary Glacial till and gravel bet Basalt east of Timber Hill (middle Pleistocene) A m5 Basaltic andesite cone north of Aspen Crater (middle Pleistocene) J mug* Basaltic andesite under Giant Crater lava field (middle Pleistocene) B, C, D, E drs* Dacite of Red Shale Butte (late Pleistocene) L, M Moraine crest Moraine crest bgc Basalt of Giant Crater (late Pleistocene) A, B m6 Basaltic andesite cone northwest of Lookout Butte (middle Pleistocene) G mwc Basaltic andesite in western Callahan Flow (middle Pleistocene) G ds* Dacite of south flank (middle Pleistocene) M Azimuth of ice movement 41°40' 41°40' bgd Basalt of Gold Digger Pass (late Pleistocene) G, H m7 Basaltic andesite cone northeast of Aspen Crater (middle Pleistocene) J mwd Basaltic andesite west of Devils Homestead (middle Pleistocene) H dsk* Dacite southwest of Kelley Pass (middle Pleistocene) F Dike Direction of ice movement Fourmile Hill Approximate ice limit, post-180 ka bgf Basalt west of Canby Cross at Gillem Fault (middle Pleistocene) H m8 Basaltic andesite cone northwest of Fourmile Hill (middle Pleistocene) G mwg Basaltic andesite west and north of Grasshopper Flat (middle Pleistocene) C dta* Dacite tuff of Antelope Well (middle Pleistocene) B, C, D, E, F, G, H, K, L Vent Possible ice limit, 250 ka (hachures bh Basalt of Hill 22 (middle Pleistocene) F m9 Basaltic andesite cone southwest of Aspen Crater (middle Pleistocene) J mwr* Basaltic andesite west of Red Cap Mountain (middle Pleistocene) D, E dwm Dacite west of Medicine Lake (middle Pleistocene) E on ice side) Littoral cone Caldera rim bhi Basalt of Hambone Island (middle Pleistocene) A m10 Basaltic andesite cone southeast of Aspen Crater (middle Pleistocene) J mws Basaltic andesite west of Squaw Peak (middle Pleistocene) D, E RHYOLITE 121°45' Argon sample locality 5800' 7913' bhp* Basalt of Hovey Point (middle Pleistocene) I m11 Basaltic andesite cone west of Medicine Lake (middle Pleistocene) D, E rcb* Rhyolite near Cougar Butte (middle Pleistocene) K 6200' ANDESITE 7400' 7000' Drill-hole locality 6600' Mount bl* Lake Basalt (late Pleistocene) I, J, K, L, M m12 Basaltic andesite cone southwest of Medicine Lake (middle Pleistocene) C, D a1 Andesite cone west of Crescent Butte (middle? Pleistocene) I rcg Rhyolite west of Crater Glass Flow (middle Pleistocene) E Hoffman Approximate topographic boundary of Medicine Lake caldera Medicine blh* Basalt of Little Mount Hoffman (middle Pleistocene) E m13 Basaltic andesite southwest of Kephart (middle Pleistocene) L a2 Andesite of Red Butte (middle Pleistocene) I rec* Rhyolite east of Callahan Flow (middle Pleistocene) H Lake bls* Basalt of Little Sand Butte (late Pleistocene) K m14 Basaltic andesite cone southeast of Paynes Springs (middle Pleistocene) M a3 Andesite of Island Butte (middle Pleistocene) H reg* Rhyolite east of Glass Mountain (middle Pleistocene) K, L Center point for azimuths of radial sector boundaries (see “Sector Location 7400' Map”) 7000' bma Basalt southeast of Mammoth Crater (late Pleistocene) I m15 Basaltic andesite cone south of Little Glass Mountain (middle Pleistocene) C a4 Andesite cone west of Cougar Butte (middle Pleistocene) J rgf* Rhyolite of Grasshopper Flat (middle Pleistocene) B, C, G K 6600' 6600' 75° Typhoon 6600' End of radial sector boundary, showing sector letters and approximate azimuthal Mesa 6200' 7000' bmc* Basalt of Mammoth Crater (late Pleistocene) G, H, I, J, K m16 Basaltic andesite cone north-northeast of Six Shooter Butte (middle Pleistocene) A a5 Andesite cone east of Fourmile Hill (middle Pleistocene) H, I rgm Rhyolite of Glass Mountain (Holocene) K, L L angle (see “Sector Location Map”)

6200' 6200'

6600' 5800' 5800'

6200'

41°30' 41°30' Six Shooter 0 3 KM Butte

121°45' 121°30' Figure 7. Map showing distribution of ice-related deposits, direction and azimuth of ice movement (in part based on glacial striations), and Geologic Map of Medicine Lake Volcano, Northern California probable ice limits at various times during history of Medicine Lake volcano. Ice apparently moved away from caldera, but it also accumulated within caldera and flowed out lowest (southeast) side, leaving striations and morainal deposits of gravel. Morainal ridges are present in large area By of till approximately 3 km south-southeast of Medicine Lake. Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government. Julie M. Donnelly-Nolan For sale by U.S. Geological Survey, Information Services, Box 25286, Federal Center, Denver, CO, 80225, 1–888–ASK–USGS 2010 Digital files available at http://pubs.usgs.gov/sim/2927/