Group 1.
Group 1 rocks (Pz and Mzg) are unconformably overlain by Group 2 (Tmvs) and Group 3 (Tmbkc, Tmblol, Tmdtomb)) rocks.

Pz
Typical mineralogy of these foliated garnet-epidote paragneisses is 30-50% quartz and 50-70% remaining minerals (e.g., plagioclase > epidote > garnet > calcite and dolomite).

Mzg
Mzg is a medium-grained, granular-textured granite composed of potassium feldspar, plagioclase, quartz, muscovite, biotite and minor garnet.

Group 2.
Tmvs is deposited unconformably upon Group 1 rocks, and is unconformably overlain by the other Group 2 unit (Tmrbio), and rocks from Groups 3 (Tmbkc, Tmblol, Tmdtomb), 4 (Tmrsf), 5 (Tmatoro), 6 (Tmrsiw, Tmr3, Tmr4, Tmrao, Tmrec) and 7 (Tmahem). Tmrbio is deposited unconformably upon the other Group 2 unit (Tmvs), and is unconformably overlain by rocks from Groups 3 (Tmdtomb), 4 (Tmrsf), and 6 (Tmrsiw, Tmr3).

Tmvs
Outcrops typically weather to pale blue or pink, and less commonly pale yellow, grey, tan, red, green, white, orange, brown, black, or a mixture of colors. The ashy matrix contains phenocrysts of quartz, feldspar, biotite, amphibole, pyroxene, and olivine. The groundmass is cryptocrystalline with ? 10% pumice and 20-35% phenocrysts which aveerage 1-2 mm. The most common clast lithology is porphyritic andesite with typical phenocryst assemblages of 7-15% plagioclase feldspar, 3-6% amphibole, and minor amounts of clinopyroxene ± olivine ± biotite in a microcrystalline groundmass.

Tmr_bio
Tmr_bio  contains 15-25% phenocrysts of plagioclase and potassium feldspar > amphibole > quartz ? biotite with trace amounts of pyroxene and Fe oxides. The cryptocrystalline matrix contains volcanic lithic fragments (10-15%) and pumice (10-15%). Pleochroic amphibole phenocrysts are a distinct forest-green (in plane light). This differs from the characteristically brown, pleochroic amphiboles ("basaltic hornblende"?) within the lithic fragments. Lithic clasts are commonly hornblende-phyric andesite but include coarse-grained (granitic) igneous rocks.

Group 3.
Tmblol is unconformably overlain by one Group 6 unit (Tmr3), and Tmbkc is unconformably overlain by one of the other Group 3 units (Tmdtomb) and by several Group 6 rocks (Tmrsiw, Tmr3, Tmr4, Tmrec). Tmdtomb is deposited unconformably upon Group 2 rocks (Tmvs, Tmrbio) and is unconformably overlain by one of the other Group 3 units (Tmbkc), and rocks from Groups 4 (Tmrsf), 5 (Tmatoro), and 6 (Tmrsiw, Tmr3, Tmr4, Tmrec).

Tmb_kc
Tmb_kc contains 6-17% phenocrysts of plagioclase (andesine [Ab_61-64An_30-37Or_2-6] and labradorite [Ab_31-36An_63-68Or₁]) ? quartz ? olivine [(Fe²⁺_0.72-0.88Mg_0.12-0.28)₂SiO₄]) > clinopyroxene (augite [(Na_0.03Ca_0.76Fe²⁺_0.19-0.24Mg_0.84-0.92Fe ³⁺_0.00-0.07Ti_0.01-0.02)(Al_0.16-0.17Si_1.87-1.92)O₆] and subcalcic augite [(Na_0.06Ca_0.49Fe²⁺_0.35Mg_0.84Fe³⁺_0.19Ti_0.05)(Al_0.27Si_1.75)O₆]) ? amphibole ([hornblende] and cummingtonite [(Mg_0.60Fe²⁺_0.40)₇Si₈O₂₂(OH)₂]) in a seriate-textured, in some cases trachytic, groundmass. Quartz xenocrysts (usually 3-4%) are rimmed with aggregates of needle-like minerals (possibly hypersthene?). Vugs ? 1 cm in diameter contain aggregates of quartz.

Tmb_lol
Tmb_lol has a devitrified, hyalopilitic groundmass with microphenocrysts of equant plagioclase crystals. Tmb_lol consists of 16-29% phenocrysts of plagioclase feldspar (andesine [Ab_51-60An_38-47Or₂]) >> orthopyroxene (hypersthene [(Fe²⁺_0.42Mg_0.58)SiO₃] and bronzite [(Fe²⁺_0.17Mg_0.83)SiO₃]) and clinopyroxene (diopside [(Na_0.02Ca_0.85Fe²⁺_0.16Mg_0.87Fe³⁺_0.03Ti_0.01)(Al_0.15Si_1.91)O₆]) ? olivine [(Fe²⁺_0.18Mg_0.82)₂SiO₄]) > amphibole ([hornblende]) and trace amounts of Fe oxides (ilmenite [(Mn_0.01Fe²⁺_0.77Mg_0.10Fe³⁺_0.25Ti_0.88)O₃]).

Tmd_tomb
The many flows which are included in Tmd_tomb exhibit a range of mineralogy. Phenocryst content ranges from 10-25% commonly in a fine-grained trachytic groundmass with feldspar microphenocrysts. Both pilotaxitic and hyalopilitic textures exist. The most common phenocryst assemblage is amphibole ([hornblende] and cummingtonite [(Mg_0.52Fe²⁺_0.48)₇Si₈O₂₂(OH)₂]) ? plagioclase (andesine [Ab_49-64An_33-49Or_2-8]) > orthopyroxene (bronzite [(Fe²⁺_0.21Mg_0.79)SiO₃]) ? quartz with trace amounts of Fe oxides ± olivine ± biotite. Hornblende phenocrysts are commonly altered to black oxides in both the groundmass and the lithic fragments, and plagioclase phenocrysts generally have mottled rims (glass inclusions?). Some samples show trace amounts of disequilibrium quartz while others show quartz apparently in equilibrium. Lithic fragments are principally igneous intrusive xenoliths such as granite (hornblende, biotite, plagioclase, and quartz) and hornblendite (?) (hornblende > plagioclase > biotite). Gneissic clasts are also present.

A shallow andesitic intrusion mapped with Tmd_tomb is a pyroxene-hornblende-plagioclase-phyric andesite with 17-27% phenocrysts of labradorite [Ab_38-49An_56-61Or₁] > amphibole ([hornblende] and grunerite [(Fe²⁺_0.71Mg_0.29)₇Si₈O₂₂(OH)₂]) > orthopyroxene (hypersthene [(Fe²⁺_0.30-0.31Mg_0.69-0.70)SiO₃]) > clinopyroxene (augite [(Na_0.03Ca_0.82Fe²⁺_0.14Mg_0.84Fe³⁺_0.06Ti_0.02)(Al_0.23Si_1.85)O₆]) and minor potassium feldspar and Fe oxides in a cryptocrystalline groundmass.

Group 4.
Tmrsf unconformably overlies rocks from Groups 2 (Tmvs, Tmrbio) and 3 (Tmdtomb), and is in unconformable contact with overlying rocks from Groups 5 (Tmatoro) and 6 (Tmrsiw, Tmr3).

Tmr_sf
Tmr_sf  contains 6-15% phenocrysts of anorthoclase [Ab_66-68An_5-6Or_26-28] and sanidine [Ab₅₆An₃Or₄₁] >> trace amounts of orthopyroxene, amphibole, quartz, and Fe oxides. The basal vitrophyre has a glassy, eutaxitic-textured matrix of welded pumice and shards, whereas the overlying stony portions are devitrified and show evidence of vapor phase crystallization. Anorthoclase phenocrysts average 1-2 mm (max. 5 mm). Orthopyroxene is green in plane light, and the pleochroic amphibole is pale tan to brown. The matrix of the uppermost, less densely welded portion is composed of devitrified glass shards.

Group 5.
Tmatoro unconformably overlies rocks of Groups 2 (Tmvs), 3 (Tmdtomb), and 4 (Tmrsf), and is unconformably overlain by some Group 6 rocks (Tmrsiw, Tmr3).

Tma_toro
Tma_toro is a trachytic andesite with a cryptocrystalline groundmass comprised of 30-45% distinctly equant (or stubby), euhedral plagioclase (andesine [Ab₅₀An₄₈Or₂] and labradorite [Ab_41-47An_52-58Or₁]) laths which average 1/8-1/4 mm on an edge. Amphibole ([hornblende]) phenocrysts (3-5%) are ? 3 mm in length. Trace amounts of Fe oxides (hematite [(Mg_0.03Fe³⁺_1.96Ti_0.02)O₃]) are also present. Rare quartz phenocrysts ? 5 mm show no evidence for disequilibrium melting, suggesting that perhaps this rock is compositionally closer to dacite rather than andesite.

Group 6.
Tmrsiw are deposited unconformably upon rocks from Groups 2 (Tmvs, Tmrbio), 3 (Tmbkc, Tmdtomb), and 4 (Tmrsf), and are conformably to unconformably overlain by other Group 6 rocks (Tmbnew, Tmr3). Tmbnew is unconformably deposited upon another Group 6 unit (Tmrsiw) and is unconformably overlain by up to 40 meters of a heterolithologic sedimentary breccia which includes well-rounded lithic fragments (clast-supported and up to boulder-size) of granite, vitrophyre, breccia, and one of the Group 6 units (Tmr3). The breccia is overlain by another Group 6 unit (Tmr4). Tmr3 unconformably overlies rocks from Groups 2 (Tmvs, Tmrbio), 3 (Tmbkc, Tmblol, Tmdtomb), and 4 (Tmrsf), conformably overlies one of the Group 6 units (Tmrsiw), is conformably overlain by another Group 6 unit (Tmr4) and by one from Group 7 (Tmahem). Tmr4 unconformably overlies rocks from Groups 2 (Tmvs), 3 (Tmbkc, Tmdtomb), and one other Group 6 unit (Tmr3), and is conformably overlain by other Group 6 rocks (Tmrao, Tmrec). Tmrao unconformably overlies Group 2 rocks (Tmvs), conformably overlies other Group 6 rocks (Tmr4) and is conformably overlain by another Group 6 unit (Tmrec). Tmrec unconformably overlies rocks from Groups 2 (Tmvs) and 3 (Tmbkc, Tmdtomb), conformably overlies some Group 6 rocks (Tmr4, Tmrao), is conformably overlain by other Group 6 rocks (Tmrbs, Tmrfp), and is unconformably overlain by all Group 7 units (Tmagem, Tmrcan, Tmaugl, Tmahem,). Tmrbs conformably overlies one of the Group 6 units (Tmrec), conformably underlies another Group 6 unit (Tmrfp), and unconformably underlies three Group 7 units (Tmagem, Tmaugl, Tmahem). Tmrfp is deposited conformably on some Group 6 rocks (Tmrbs, Tmrec) and is unconformably overlain by Group 7 rocks (Tmaugl, Tmagem).

Tmr_siw
The most distinctive features of the phenocryst mineralogy in Tmr_siw are the general absence of quartz, hornblende, or significant amounts of biotite, and the presence of disequilibrium olivine. The unit consists of 10-20% phenocrysts of plagioclase (andesine [Ab_57-68An_27-41Or_2-5] and oligoclase [Ab_70-73An_20-25Or_5-7]) and anorthoclase ([Ab_63-70An_6-11Or_19-31]) >> olivine ? clinopyroxene (ferroaugite [(Na_0.02Ca_0.80-0.83Fe²⁺_0.73-0.87Mg_0.25-0.41Fe³⁺_0.01Ti_0.01)(Al_0.03-0.04Si_1.98-1.99)O₆] and [pigeonite]) ? Fe oxides (hematite [(Mn_0.03Fe²⁺_0.12Mg_0.02Fe³⁺_1.66Ti_0.17)O₃]) ± trace biotite. The olivine is altered black or red (probably "iddingsite") around the edges and internally along fractures, and in some crystals a prismatic habit is well-defined. The orthopyroxene is distinctly green (but not pleochroic) in plane light. Some olivine and orthopyroxene phenocrysts are imbedded in larger plagioclase phenocrysts ? 4 mm, suggesting that the country rock through which this unit erupted may have been a coarse-grained gabbro and that these are in fact xenocrysts. Some of the feldspars are mottled (glass inclusions?). The groundmass consists of vitric glass spicules and pumice which are usually colorless but can be bright yellow or pale brown in plane light; it can also have a devitrified cryptocrystalline texture. The bright yellow variety of groundmass glass is most common in cooling units t2 and t3. Lithic fragments (10-15%) average a few mm to a few cm and include fine-grained, trachytic-textured volcanic rocks, hornblende-phyric andesite (Tmdtomb), granite, and pieces of devitrified tuff. The general absence of hornblende, biotite, and quartz suggests a more anhydrous (hotter) parent magma than other tuffs bearing hydrous phases.

Tmb_new
Tmb_new contains 12-18% phenocrysts of plagioclase (bytownite [Ab₁₇An₈₃], andesine [Ab_56-60An_36-41Or_3-4], and labradorite [Ab₄₂An₅₆Or₂]) > clinopyroxene ([pigeonite] and augite [(Na_0.02Ca_0.78Fe²⁺_0.42Mg_0.73Fe³⁺_0.02Ti_0.01)(Al_0.06Si_1.96)O₆]) > olivine ? ilmenite [Mn_0.01Fe²⁺_0.81Mg_0.06Fe³⁺_0.24Ti_0.88)O₃] granules. Glomerocrysts of plagioclase and pyroxene are in a fine-grained groundmass with both intergranular and intersertal textures. Plagioclase laths in the groundmass form a slightly trachytic texture. Some of the euhedral to subhedral plagioclase phenocrysts are severely embayed and possibly contain glass inclusions.

Tmr3
The matrix of Tmr3 is pale brown (in plane light), devitrified, and cryptocrystalline. Phenocrysts (5-15%) include anorthoclase ([Ab_63-66An_1-2Or_32-36]) >> quartz > trace orthopyroxene and Fe oxides ± trace olivine (very altered) ± trace hornblende ± trace plagioclase. Quartz (ave. 1 mm) and anorthoclase (? 2-3 mm) are characteristically embayed (glass inclusions?). Plagioclase is rare in the groundmass. Orthopyroxene is distinctly bright green and pleochroic in plane light. Lithic fragments (? 15%) include hornblende-phyric andesites, porphyritic basalt, volcaniclastic breccia (Tmvs?), trachytic volcanic rocks (groundmass commonly altered to black), and granite (containing biotite, hornblende, feldspar, quartz, and sphene). These xenoliths could be the source of the trace amounts of hornblende and plagioclase in Tmr3.

Tmr_3-4 (unit between Tmr3 and Tmr4)
Tmr_3-4 is an unwelded to moderately welded, vitric ash-flow tuff with < 1% phenocrysts of feldspar and pyroxene. The phenocrysts average < 1 mm and the pyroxenes are characteristically green in plane light. The groundmass consists of glass spicules and pumice. Lithic fragments include altered trachytic volcanic rocks consisting primarily of plagioclase laths.

Tmr4
This densely welded ash-flow tuff contains < 1% feldspar (ave. 1/8-1/4 mm) and clinopyroxene phenocrysts in a spherulitic, devitrified groundmass. Lithophysae contain vapor phase crystals of tridymite (?) and some calcite infilling.

Tmr_ao
Some samples of Tmr_ao are glassy while others are devitrified. Tmr_ao  contains a maximum of 2% phenocrysts of feldspar (plagioclase and anorthoclase (?)) and orthopyroxene. The densely welded versions are devitrified with vapor phase crystallization. Calcite cement is common in vugs, and rare glass spicules in vitric samples are yellow or brown. One quartz phenocryst was found in one thin section. Lithic fragments include altered trachytic volcanic rocks and porphyritic volcanic rocks which may be pieces of Tmd_tomb. One sample has a lithic fragment which is probably from Tma_toro.

Tmr_ec
Tmr_ec contains 3-10% phenocrysts of feldspar (oligoclase [Ab_71-74An_19-23Or_5-7] and anorthoclase [Ab_50-58An_3-5Or_37-47]) >> orthopyroxene ? Fe oxide granules (magnetite [(Fe²⁺_1.27Mg_0.04Fe³⁺_1.35Al_0.03Ti_0.31)O₄]). Amphibole [hornblende] was identified with the electron microprobe but not observed in thin section; some of the altered minerals may be of this composition. The feldspars (? 2.5 mm) are distinct in thin section from feldspars described in other units in this study because they almost always contain brittle fractures or veins filled with a high birefringence material (calcite?). Pleochroic orthopyroxene is green and pink and can be altered to black around the rims. The groundmass is partially to completely devitrified, densely welded, microcrystalline with secondary vapor phase quartz (tridymite?) in the lithophysae, and most samples contain secondary calcite (?) cement. Lithic fragments are rare; a 1.5 mm lithic clast in one thin section was completely altered to black and retained no identifiable features.

Tmr_bs
The welded groundmass of Tmr_bs  is microcrystalline with microphenocrysts of feldspar and Fe oxide granules. The rock is devitrified and contains vapor phase crystallization of quartz in the lithophysae. There are 5-10% phenocrysts of feldspar (plagioclase and anorthoclase (?)) > Fe oxides with trace amounts of altered mafic phenocrysts (pyroxene?).

Tmr_fp
Tmr_fp is a densely welded, devitrified tuff with 4-9% phenocrysts of plagioclase and anorthoclase feldspars > Fe oxides > orthopyroxene with trace amounts of altered olivine (?). Lithic fragments (~1%) include very altered porphyritic volcanic rocks which average 1-1.5 mm.

Group 7.
Tmagem unconformably overlies some Group 6 units (Tmrec, Tmrbs, Tmrfp) and unconformably underlies one of the other Group 7 units (Tmrcan). Tmrcan unconformably overlies rocks of Groups 6 (Tmrec) and another Group 7 unit (Tmagem). Tmaugl unconformably overlies Group 6 rocks (Tmrec, Tmrbs, Tmrfp). Tmahem unconformably overlies rocks from Groups 2 (Tmvs) and 6 (Tmr3, Tmrec, Tmrbs).

Tma_gem
Tma_gem is a seriate-textured andesite with 13-16% phenocrysts of stubby plagioclase laths (labradorite [Ab_32-35An_64-68Or_0-1] and bytownite [Ab₂₀An₈₀]) > orthopyroxene (bronzite [(Fe²⁺_0.17-0.21Mg_0.79-0.83)SiO₃]) and clinopyroxene (diopside and augite [(Na_0.02Ca_0.79-0.83Fe²⁺_0.15-0.21Mg_0.87-0.92Fe³⁺_0.04-0.05Ti_0.02-0.03)(Al_0.11-0.14Si_1.89-1.91)O₆] > Fe oxides. The plagioclase averages 1/4-1 mm and the pyroxenes are commonly 2 mm (max. 4 mm). Some samples have a trachytic texture with sub-parallel alignment of feldspar microphenocrysts in a fine-grained groundmass. The groundmass glass can be altered to red or black. The pyroxene phenocrysts are altered around the rims and within fractures.

Tmr_can
Tmr_can contains 3-8% phenocrysts of feldspar (oligoclase [Ab_69-71An_20-22Or₉]) > Fe oxides (magnetite [(Fe²⁺_1.25Mg_0.04Fe³⁺_1.26Al_0.16Ti_0.29)O₄] and ilmenite [(Mn_0.01Fe²⁺_0.68Mg_0.03Fe³⁺_0.55Ti_0.73)O₃]) ? clinopyroxene (augite [(Na_0.01-0.02Ca_0.84-0.87Fe²⁺_0.19-0.24Mg_0.85-0.88Fe³⁺_0.00-0.01Ti_0.01)(Al_0.04-0.10Si_1.94-1.98)O₆]) and orthopyroxene (bronzite [(Fe²⁺_0.19Mg_0.81)SiO₃]), and notably lacks quartz. Feldspars are ? 2.5 mm and are commonly mottled (glass inclusions?) and orthopyroxene can be altered black around the rims and along fractures. Pyroxene phenocrysts are < 0.5 mm in size, in marked contrast to larger pyroxene phenocrysts in Tma_hem and Tma_gem. Tmr_can  has a cryptocrystalline to microcrystalline, seriate-textured matrix of feldspar microphenocrysts in a fine-grained, glassy groundmass. Tmr_can is usually devitrified, and spherulitic halos are present in many of the thin sections. Secondary calcite commonly fills fractures and vugs. Also common in this unit are pockets filled with interstitial-textured needles of feldspar and needle-like mafic phenocrysts. Gabbroic xenoliths (< 1%) up to several cm consist of labradorite [Ab_31-33An_67-69], bronzite [(Fe²⁺_0.23-0.24Mg_0.76-0.77)SiO₃] and minor clinopyroxene.

Tma_ugl
Tma_ugl consists of 9-16% phenocrysts of euhedral plagioclase > orthopyroxene > Fe oxides in a microcrystalline groundmass with an intersertal texture. Glomerocrysts of all three phenocryst types are ? 5 mm but are fairly uncommon. Some of the groundmass is altered to red (in plane light), and some of the pyroxene phenocrysts have red or black altered rims. Many of the plagioclase phenocrysts are extensively mottled (glass inclusions?).

Tma_hem
Tma_hem is an intersertal-textured andesite with euhedral to subhedral phenocrysts (10-30%) of plagioclase (labradorite [Ab_37-38An_61-62Or₁] and bytownite [Ab₁₆An₈₄]) > orthopyroxene (bronzite [(Fe²⁺_0.17-0.29Mg_0.71-0.83)SiO₃] > clinopyroxene (diopside [(Na_0.02Ca_0.85-0.87Fe²⁺_0.12-0.14Mg_0.91-0.93Fe³⁺_0.02-0.03Ti_0.01)(Al_0.09-0.10Si_1.94-1.95)O₆]). The groundmass consists of microphenocrysts of feldspar and interstitial glass. The clinopyroxene and orthopyroxene phenocrysts make up one-third of the phenocrysts and in many cases the largest phenocrysts (? 5 mm) appear to be composites of several grains.