Scientific Investigations Map 2899 U.S. Department of the Interior Sheet 2 of 3 U.S. Geological Survey Pamphlet and CD-ROM accompany map GLACIAL, SEDIMENTARY AND HYDROTHERMAL DEPOSITS VOLCANIC CENTERS OF SOUTHERNMOST CASCADES 1917 C.E. p17 Phreatic deposit, May–June w2 Viscous debris-flow deposits, May 22 p2 Pumice-fall deposit, May 22 pw2 Pyroclastic-flow and associated fluid debris-flow deposits, May 22 Deposits of 1914–1917 eruption of Lassen Peak 1915 C.E. d9 Dacite flow, May 19–20 f9 Flood deposits, May 19–20 sw9 Avalanche and debris-flow deposits, May 19–20 p9 Pyroclastic deposit, May 19 CORRELATION OF MAP UNITS HEADNOTE d4 Dacite dome, May 14–19 [See Description of Map Units (pamphlet) for detailed unit descriptions and interpretation of unit ages; ages shown may be averages of several ages. See table 2 and references in unit descriptions for age analysis information. Fantastic mf2 Flow 2 Units of volcanic centers and the Caribou Volcanic Field are shown on colored backgrounds for emphasis. Sequences are groups of volcanoes related by lithology and age. Chains are sequences displaying conspicuous linear Lava Beds mf1 Flow 1 geometry. Indentations in left margin of Lassen Volcanic Center area indicate intercalations with glacial and surficial units. Age boundaries based on Gradstein and others (2005) and Walker and others, 2009. Paleomagnetic Basaltic andesites of Cinder Cone 1666 C.E. mp2 Flow 2 polarity (+, normal; -, reversed) boundaries based on Berggren and others (1995). C.E., Common Era. Unit age is left of unit box; unit name is right of unit box. Some unit boxes represent groups of units, such as the unit box Qsh Landslide h Hydro- ht Travertine Painted mp1 Flow 1 labeled bb, which is not a unit on the map. A note in parentheses to the right of the unit name shows that the box represents units bb1–bb6 and bb8–bb12. Colored arrows pointing up and down from unit boxes indicate the deposits in thermally Dunes mo Old Bench flow possible range in age of unit. See table 3 for alphabetical listing of map unit labels, as well as unit name, page number of unit description in pamphlet, unit age, location by heading in Correlation of Map Units, and quadrangle hydrothermally altered rocks 278±28 yr B.P. Qsj Avalanche deposits of Chaos Jumbles location in database] altered core of in active HOLOCENE Brokeoff thermal areas rcf Volcano Talus, emplaced pce Lithic pyroclastic-flow deposit from REGIONAL VOLCANIC ROCKS hot from rce partial collapse of dome E domes B–F pcd Lithic pyroclastic-flow deposit from Qf Alluvium Qc Colluvium cc Domes partial collapse of dome D and talus A–F rcd Rhyodacite of Chaos Crags rcc NORTH AND WEST OF LASSEN VOLCANIC CENTER SOUTH AND EAST OF LASSEN VOLCANIC CENTER REGIONAL VOLCANIC ROCKS OF THE CARIBOU AREA Qd Diatomite rcb rca 1,103±13 yr B.P. pc Pumiceous pyroclastic-flow Late Pleistocene volcanic rocks 3,310±55 yr B.P. and fall deposits ~8,000 yr B.P. Qwh Debris-flow deposits from the northeast side of Lassen Peak Qth Till or protalus-rampart debris ? 11.7 Qtal Late till of ka* Anklin Meadows a74 Andesite of hill 7416 atd Andesite of Devils Rock Garden Qta Till of Anklin Meadows Qoa Outwash gravel of Anklin Meadows Twin Lakes sequence, younger Twin Qcl Talus on Lassen Peak Qtrl Post-maximum till of Raker Peak consisting of Lassen Peak avalanche debris Eagle Peak sequence mtt Qty Till, younger Qoy Outwash Qou Outwash Qsl Avalanche debris from Lassen Peak spread across glacial ice Basaltic andesite of Turnaround Lake glaciations gravel, gravel, 24±6 ka bhc Hat Creek Basalt mrc Basaltic andesite of Red Cinder Cone Lithic pyroclastic-flow deposit younger undivided 27±1 ka pfl (tholeiitic) glaciations from partial collapse of dome Dacite of Lassen Peak dl Tumble brc Dome adb Andesite of Bidwell Spring Basalt of Red Cinder Cone Buttes Qtr Till of Raker Peak Qor Outwash gravel of Raker Peak chain 35.1±3.1 ka atb Andesite of Bear Wallow Butte mrr Basaltic andesite of Red Cinder mdp Basaltic andesite of Pole Spring Road rk Flows mt67 Basaltic andesite of hill 6770 Rhyodacite of Kings Creek 35±1 ka pk Pumiceous pyroclastic-flow deposits mt54 Basaltic andesite of hill 5410 Bidwell br80 Basalt of hill 8030 mtu Basaltic andesite md36 Basaltic andesite of section 36 rsf Domes of Tumble Buttes Spring Rhyodacite of Sunflower Flat chain brm Basalt of Cameron Meadow 41±1 ka psf Pumiceous pyroclastic-flow deposits mtb Basaltic andesite of Bear Wallow Butte Red Tuya 43±2 ka rkr Rhyodacite of Krummholz ah Andesite of Hat Mountain mt61 Basaltic andesite of hill 6138 bra Basalt of Ash Butte 46±7 ka ass Andesite of Sugarloaf Peak 46.3±3.4 ka bdt Basalt of Twin Buttes Cinder chains mt5 Basaltic andesite of section 5 chain ? ? mdb Basaltic andesites of Black Butte (Units 1–2) br22 Basalt of hill 2283 att Andesite of Tumble Buttes r27 Rhyodacite of section 27 mte Basaltic andesites mtm Basaltic andesite of Mud Lake ae Andesite of Eagle Peak br25 Basalt of section 25 ? of Evelyn Lake bk Tholeiitic basalts of 65±45 ka bbz Tholeiitic basalts of Big Lake (units 1–2) Sugarloaf 66±4 ka re 67±4 ka msl Basaltic andesite of Buzzard Springs Dome and flow chain 69±20 ka arr Andesite of Red Cinder Rhyodacite of Eagle Peak Lassen domefield Little Potato Butte bic Tholeiitic basalt of pe Pumiceous pyroclastic-flow deposits Ice Cave Mountain bre Basalt east of Ash Butte PLEISTOCENE LATE 77±11 ka asp mrd Basaltic andesite and andesite Andesite of Potato Butte meh Basaltic andesite brw Basalt of Widow Lake 82±14 ka mfp Basaltic andesite of Fairfield Peak of Red Lake Mountain ms47 Basaltic andesite of hill 4709 of Eskimo Hill mrg Basaltic andesites of Long Lake (Units 1–3) 93±13 ka ac Qtb Andesite of Crater Butte aso Andesites of Old Station 97.6±9.8 ka bc Basalts of Cone Lake Road (Units 1–2) Till of Badger Mountain mrm Basaltic andesite of Red Mountain mrb Basaltic andesite of Caribou Wilderness bcc Basalts of Cold 102.1±11.4 ka bg Basalts of old railroad grade (Units 1–4) brt Basalts of Triangle Lake (Units 1–2) Creek Butte 105.0±6.0 ka bp Basalts of Poison Butte (Units 1–6) ? mte Basaltic andesites 107.5±3.8 ka Basalts and basaltic andesites bb of Evelyn Lake 100.1±8.5 ka of Bogard Buttes (Units 1–6; 8–12) Poison 106.2±3.6 ka bpc Basalts of Pine Creek (Units 1–3) Lake Qto Till, older Qoo Qou Outwash gravel, 101.0±1.9 ka Outwash chain bt Basalts of Pittville Road (Units 1–4) glaciations gravel, undivided bmc Tholeiitic basalts of 108±14 ka older Mill Creek Plateau m20 Basaltic andesite west of hill 2078 glaciations Middle Pleistocene and older volcanic rocks 108.6±2.1 ka bs Basalts of Stephens Campground (Units 1–5) 110.8±3.8 ka 101.5±8.7 ka br Basalts of Robbers Spring (Units 1–5) 125 ka* 143±6 ka mbg Basaltic andesite of Little Bunchgrass Meadow ? ? ? mbx Basaltic andesite of Box Canyon 167±4 ka Basalts and basaltic bsm msm 172±23 ka andesites of Sifford Basaltic andesite of Small Butte Brunhes (+) Mountain 193±11 ka rd Rhyodacite of Dersch Meadows 199±22 ka bec Tholeiitic basalt of 190±18 ka b44 Tholeiitic basalt of b18 Tholeiitic basalt 188±32 ka Eagle Canyon Calif. Hwy 44 of hill 1879 amh Andesite and basalt of Mount Harkness 210±120 ka 212±5 ka dr Dacite of Reading Peak 232±8 ka db Dacite of Bumpass Mountain bn Tholeiitic basalt of Nobles Trail 236±1 ka dc Dacite of Crescent Crater mm Basaltic andesites of 202.0±2.2 ka bl35 Basalt of section 35 Qs82 Avalanche deposit 244±10 ka ds Dacite of Ski Heil Peak Magee Volcano from dacite of 247±56 ka ap Andesite and basaltic andesite bl2 Basalt of section 2 bl20 Basalt of hill 2088 249±12 ka dh Dacite of Mount Helen hill 8283 of Prospect Peak Cone bl30 Basalt of section 30 duh Dacite under Mount Helen dsc Dacite of acl Andesite and basaltic Summit Creek andesite of Cluster Lake 220±14 ka bl22 Basalt of hill 2232 dpl Dacite of Lassen Peak parking lot dv Dacite of Bumpass Lakes chain bl21 Basalt of hill 2109 261±5 ka d82 Dacite of hill 8283 Vulcans Castle sequence ? mlc Basaltic andesites of Cone Lake ml18 Basaltic andesite of hill 1868 270±18 ka arp Andesite of Raker Peak pdh Lithic tephra from dmz Dacite of upper Manzanita Creek Triangle Deep Hole mtr Lake 277±22 ka Basaltic andesite of Triangle Lake sequence mt20 Basaltic andesites of section 20 297±1 ka rmz beb Basalts of Bond Valley (Units 1–3) Rhyodacite of Manzanita Chute mhl Basaltic andesite of Echo Twin Lakes sequence, older Twin 302±7 ka bsl Basalt of Lost Spring Lake 302±36 ka mee 298±9 ka rmc Rhyodacite of Mount Conard Huckleberry Lake Basaltic andesites of Echo Lake (Units 1–2) bsd Basalt of Duck Lake sequence mes rlm Rhyodacite of Loomis Peak Basaltic andesite of Star Butte 313±8 ka av Andesite of Viola bct Basalt of bo Basalt of Onion Springs Island bii Basalt of mce Basaltic andesite mcj Basaltic andesite mcr Basaltic andesite Cherry Caribou Thicket awp Andesites of West Lake Island Lake of Eleanor Lake of Jewel Lake of Rim Lake Prospect Peak Sunrise chain mcn Basaltic andesites of North Caribou (Units 1–8) bbf Basalt of Badger Flat sequence 331±45 ka bie Basalt of QUATERNARY Peak East Lake bcs Basalt of South Caribou sequence 362±33 ka mcm Basaltic andesite of middle Caribou Caribou bcw mch Basaltic andesite of Hay Meadow Basalt of sequence Caribou mc71 Basaltic andesite of hill 7114 Wilderness bs72 Basalt of hill 7243 bci Basalt of Indian Meadow 393±4 ka bss Basalts of Sunrise Peak (Units 1–2) 400±14 ka mc Basaltic andesites of 387±10 ka amd Andesite of Mount Diller bsb Basalt of Bathtub Lake bcp Basalt of Silver Lake (Units 1–11) Caribou Peak Qwb Debris-flow deposit bcb from Brokeoff Volcano Basalt of Cowboy Lake