SIM 2940 - Additional photographs

Additional photographs to accompany

Geologic Map of the North Cascade Range

We provide additional photographs of the rocks and deposits described in the geologic map. These photographs also present some of the landscape and scenery of the range. As is commonly the case, the selection is biased towards sunny days and above-timberline settings. Not all the North Cascade Range looks like this all the time.

Below, photo captions are listed in alphabetical order by the 2- to 4-letter tag for the most significant geologic map unit shown and are linked to the photos. Photos are also linked to the Correlation of Map Units diagram; note that not all map units have corresponding photos. Photos are also linked to their locations as shown on a simplified map of the range. A few photos are presented with multiple captions that emphasize different geologic map units. The date of photography is given for some photos in which temporal changes in the extent of snow cover may be of interest.

Previous photo and Next photo links with the individual photo pages step through the photos in the order below.

Jis-1. Mount Stuart, viewed from point near Lake Ingalls [Wnw], is granodiorite and quartz diorite of the Mount Stuart batholith, included in the Late Cretaceous tonalitic stitching plutons (Kt). The batholith intruded ultramafic rock of the Ingalls terrane (Jis), which crops out in the lower slopes of the peak and in the foreground.
Jnbm-1. Metamorphic rocks of McClure Mountain (Jnbm) exposed in roadcut along Gold Creek road [Tse].
JTrc-1. Cultus Formation of Brown and others (1987) (JTrc) of the Chilliwack River terrane. Typical outcrop of finely laminated tuffaceous argillite near Canadian border, north of Bald Lake [MBnw].
Ked-1. Dark rock at bottom of photograph is typical Darrington Phyllite (Ked) with deformed quartz segregation veins. Here, phyllite is structurally overlain by metachert and (at top of picture) Shuksan Greenschist (Kes). Headwaters of Noisy Creek, east of Mt Watson [MBsw].
Kes-1. Shuksan Greenschist (Kes, Easton Metamorphic Suite of the Easton terrane) outcrop in Sulphide Creek cirque [MBnw]. Note folded foliation. Bundled crampons for scale.
Kes-2. Isoclinally folded Shuksan Greenschist (Kes) on north side of Anderson Butte [MBsw].
Kes-3. View to southeast from Anderson Butte of Shuksan Greenschist (Kes, Shuksan nappe of the Northwest Cascade System) exposed on north face of Mount Watson [MBsw]. Distant peaks are in Chelan block. Photographed in 1978.
Kes-4. View west from Bacon Peak [MBsw]. Rocks of Easton Terrane crop out in foreground (Darrington Phyllite, Ked) and form Anderson Butte (Shuksan Greenschist, Kes). A huge block of ultramafic rock (dunite, KJts) in Bell Pass mélange (KJb) forms Twin Sisters. Mount Baker volcano (Qcav) dominates skyline. This photo is figure 8 in the accompanying report (sheet 2).
KJb-1. Unusually coherent thin-bedded radiolarian chert in the Bell Pass mélange (KJb) in a road cut east of Bald Mountain [MBnw].(KJb).
KJh-1. View southwest from base of Cathedral Peak [RMne]. Early Cretaceous and Jurassic hornblendic rocks (KJh) including the Spanish Camp Gneiss of Hawkins (1964), and Ashnola gabbro of Daly (1912) were intruded by Early Cretaceous tonalite and gneissic tonalite of the Remmel batholith (Kor). Upper Cathedral Lake in middle ground is a glacial tarn, carved from granite of the early Late Cretaceous Cathedral batholith of Daly (1912) (Kog). At this locale the granite is faulted against the older rocks of the Remmel batholith. Qt, talus. Fault (heavy line) and contact (thin line) dashed where approximately located and dotted where concealed or hidden.
KJn-1. Sandstone and argillite of the Nooksack Formation (KJn) on Chowder Ridge [MBnw]. Note well-developed graded beds and filled burrows to right of ice ax.
KJn-2. Volcanic grit with rounded and flattened dacite pebbles, basal Wells Creek Volcanic Member (KJnw) of the Nooksack Formation (KJn), north of Rainbow Glacier [MBnw] on the northeast side of Mount Baker.
KJos-1. Fossil of rough clam (?Trigonia sp.) in coarse-grained sandstone of the Patterson Lake unit of McGroder and others (1991), included in our rocks of the Methow Ocean, older sedimentary rocks (KJos). The sandstone here, on the west side of Patterson Mountain [Tne], was probably a beach deposit.
KJts-1. View to north of the Twin Sisters Range [MBsw] from west of Howard Creek; South Twin on left. The Range is a large slab of dunite (KJts) from the Earth’s mantle within the Bell Pass mélange (KJb). Geophysical work shows the slab to be about 1 km thick. Rock in foreground is correlated with the Darrington Phyllite (Ked) and is separated from the mélange by a high-angle fault in intervening Howard Creek canyon.
KJya-1. View west-northwest down Glacier Creek from the slopes of Mount Baker [MBnw]. A rocky prominence in the middle distance is a klippe of Yellow Aster gneiss (KJya) resting on Nooksack Formation (KJn). Qag, alpine glacial deposits. Photographed in 1990.
Kncs-1. Aerial view to north near Green Mountain [SRne]. Meadow slopes of Chiwaukum Schist (Kncs) of the Nason terrane are ribbed with erosion-resistant volcanic sills, perhaps related to Glacier Peak volcano (Qcav, out of sight to southeast). A metamorphosed fault, a major terrane suture, separates the Chiwaukum Schist from the Napeequa Schist (Kns) of the Chelan Mountains terrane. Schists of the Chelan Mountain terrane have been intruded by tonalitic plutons (Kt) and granodioritic plutons (Kg). Cretaceous rocks have then been intruded by Cascade Magmatic Arc plutons of the Cascade pass family (QTcp). Knmg, Nason Ridge Migmatitic Gneiss; Knu, ultramafic rocks; TKcs, Cascade River Schist; TKgo, Eldorado Orthogneiss. Contacts (thin lines) and faults (heavy lines) dashed where approximately located and dotted where hidden. Photographed in 1958.
Kncs-2. Relict pillows in amphibolite of Chiwaukum Schist (Kncs), Nason terrane of the Wenatchee block. Exposure northeast of White Mountain [SRse].
Knmg-1. Late Cretaceous Nason Ridge Migmatitic Gneiss (Knmg) of the Nason terrane exposed on the north ridge of Black Mountain [SRse], southwest of Glacier Peak.
Kns-1. Southwest side of Clark Mountain [Tsw] displaying Napeequa Schist (Kns) of the Chelan Mountains terrane, Chelan block. Complexly folded, light-colored layers are metamorphosed beds of ribbon chert. Cliff is about 1,400 ft (400 m) high.
Kns-2. Folded mica-rich quartzite (metachert) in Napeequa Schist at the head of Boulder Creek near Boulder Pass [Tsw].
Kog-1. View southwest from base of Cathedral Peak [RMne]. Upper Cathedral Lake in middle ground is a glacial tarn, carved from granite of the early Late Cretaceous Cathedral batholith of Daly (1912) (Kog). The granite is faulted against somewhat older Early Cretaceous tonalite and gneissic tonalite of the Remmel batholith (Kor). Remmel magmas intruded Early Cretaceous and Jurassic hornblendic rocks (KJh). Qt, talus. Fault (heavy line) and contact (thin line) dashed where approximately located and dotted where concealed or hidden.
Kor-1. Gneissic tonalite, Doe Mountain pluton of the Remmel batholith (Kor). Note flash of cleavage in large K-feldspar crystal to left of hand lens. Outcrop on south slope of Doe Mountain [RMse].
Kor-2. Wispy mafic mineral concentrations in gneissic biotite tonalite typical of parts of the Remmel batholith (Kor). Outcrop in upper Meadow Creek (RMne). This rock was mapped in the Lake Creek Gneiss by Hawkins (1968).
Kot-1. View to west from near the summit of Bunker Hill [RMne]. Low-relief uplands, seen here at 7,000 ft elevation (2,200 m) in the Okanogan block, are typical of much of the northeast corner of the map area and probably reflect significantly less late Cenozoic uplift and incision than in the Methow and Chelan structural blocks west of the Pasayten Fault. Bedrock of Bunker Hill is Early Cretaceous tonalite and gneissic tonalite (our older tonalite, Kot). Prominent pyramid on skyline is Castle Peak.
Kpc-1. View east into Pipestone Canyon [Tne] and gently dipping fluvial sandstone and conglomerate of the Late Cretaceous Pipestone Canyon Formation (Kpc). Beyond the Pasayten Fault, Early Cretaceous and Jurassic mylonitic granodiorite, gneissic trondhjemite, and banded gneiss (KJog) underlie the slopes of the Okanogan block.
Kpc-2. Coarse, monolithologic conglomerate at the base of the Late Cretaceous Pipestone Canyon Formation (Kpc), lower west side of Pipestone Canyon, Methow block [Tne]. Outcrop is about 30 m high.
Kps-1. Pebble conglomerate of the Virginian Ridge Formation of Barksdale (1975) in Pasayten Group of Kiessling and Mahoney (1997) (Kps) exposed north of Cady Pass [RMsw]. Weathering has reduced the matrix since the late Pleistocene Cordilleran Ice Sheet cut and polished harder chert pebbles.
Kps-2. View northeast from Mount Rolo of thick-bedded fluvial sandstone of the Pasayten Group (Kps) exposed on Osceola Peak [RMnw] overlying marine rocks of the Three Fools Sequence of Haugerud and others (2002) (rocks of the Methow Ocean, Ktf). Rocks along the ridge to Osceola Peak are in the upper plate of the Chuchuwanteen thrust fault; the same units crop out in the lower plate of the thrust below and to the east. Orange streaks are dacite porphyry dikes, offshoots of the granite Monument Peak stock (Tei). Kpv, volcanic rocks of the Pasayten Group; Qt, talus. Contacts (thin lines) and faults (thick lines) dashed where approximately located and dotted where concealed (covered or hidden).
Kps-3. Crossbeds in fluvial sandstone of the Pasayten Group of Kiessling and Mahoney (1997) (Kps) exposed near Tatoosh Buttes [RMnw].
Kps-4. Bioturbated siltstone in transition facies between Late Cretaceous Virginian Ridge Formation of Barksdale (1975) and Winthrop Formation of Kiessling and Mahoney (1997) exposed on Gold Ridge north of Slate Peak [RMnw]. Both units are included in the Pasayten Group of Kiessling and Mahoney (1997) (Kps).
Kps-5. Mold of stump in base of chert-gravel conglomerate bed, sedimentary rocks of the Pasayten Group of Kiessling and Mahoney (1997) (Kps). Center of stump is at knee height below outstretched hand, note radiating roots. Such stump molds are among the evidence that the Virginian Ridge Formation of Barksdale (1975) is fluvial. Hillside west of Huckleberry Creek, 2.5 km north of Gardner Mountain [RMse].
Kpv-1. View southeast down Methow River valley [RMsw]. In the middle distance volcanic rock and redbeds (Kpv) overlie fluvial sandstone (Kps), both of the Pasayten Group, in the west limb of the Goat Peak Syncline. Redbeds, the Ventura Member of Midnight Peak Formation of Barksdale (1975), also crop out on left (closer). Qt, talus; Qa, alluvium of valley bottoms. Contacts (thin lines) and faults (thick lines) dashed where approximately located. Goat Wall is about 1,100 m high.
Kpv-2. View northeast from Midnight Mountain [Tne]. We include redbeds of the Ventura Member of the Midnight Peak Formation of Barksdale (1975) in the volcanic rocks of the Late Cretaceous Pasayten Group of Kiessling and Mahoney (1997) (Kpv). Virginian Ridge is the type area of the Virginian Ridge Formation of Barksdale (1975), a unit included in the sedimentary rocks of the Pasayten Group (Kps). Big Craggy Peak [RMne] is eroded from volcanic rocks of the Pasayten Group at the northeast margin of the Pasayten block. North Twentymile Peak [RMne] is in the Okanogan block, on the far side of the Pasayten fault.
Kt-1. Mount Stuart, viewed from point near Lake Ingalls [Wnw], is granodiorite and quartz diorite of the Mount Stuart batholith, included in the Late Cretaceous tonalitic stitching plutons (Kt). The batholith intruded ultramafic rock of the Ingalls terrane (Jis), which crops out in the lower slopes of the peak and in the foreground.
Kt-2. Tenpeak Mountain [SRse] viewed from the Honeycomb Glacier to the west. Dark tonalite (Kt) forms the peak. Photographed in June 1961.
Kt-3. Cretaceous tonalite dike of Clark Mountain stock (Kt) intruding Napeequa Schist (Kns). Rotated schist fragments show magmatic nature of the deep-seated synorogenic pluton. Outcrop at head of Boulder Creek near Boulder Pass [Tsw].
Kt-4. Magmatic layering in Riddle Peaks pluton, an undeformed hornblende gabbro included in the Late Cretaceous tonalitic plutons (Kt). Outcrop at head of Hilgard Creek, north of Holden [Tsw].
Kt-5. Close view of magmatic layering in hornblende gabbro of Riddle Peaks pluton (Kt). Outcrop at head of Hilgard Creek, north of Holden [Tsw].
Ktf-1. View south from Mount Winthrop [RMnw] along crest of Cascade Range. Well-bedded sandstone of Cretaceous Three Fools Sequence of Haugerud and others (2002) (Ktf, rocks of Methow Ocean) form crest. Summit of Three Fools Peak is a thick conglomerate lens within the Three Fools Sequence. Divide at right was rounded by overriding Cordilleran Ice Sheet. Mixed glacial deposits (drift) from ice sheet and local alpine glaciers are visible in valley bottom (Qga). Qt, talus. This photo is figure 19 in the accompanying report (sheet 2).
Ktf-2. View to north of strata of Three Fools Sequence of Haugerud and others (2002) (Ktf) exposed on ridge northwest of Deception Pass [RMnw].
Ktf-3. Load casts on bottom of overturned sandstone bed in marine Three Fools Sequence of Haugerud and others (2002) exposed on ridge crest (northwest of Elbow Basin [RMnw]. Large black argillite rip-up clast in lower left corner.
MzPzh-1. View northeast to Hozomeen Mountain from ridge north of Skymo Creek [MBne]. Foreground shows disrupted bedded radiolarian chert of Hozomeen Group (MzPzh) of the Hozomeen terrane. Hozomeen Mountain and long ridge in middle ground are mostly greenstone of the Hozomeen Group.
MzPzh-2. Hozomeen greenstone (MzPzh) in Methow block north of Little Beaver Creek [MBne], where it is probably Triassic, and on Hozomeen Mountain, where it is Late Paleozoic. View northeast from ridge south of Little Beaver Creek. This photo is figure 20 in the accompanying report (sheet 2).
PDc-1. Pillow structure in greenstone of Chilliwack Group of Cairnes (1944) (PDc). North side of Rainbow Creek [MBnw].
Qa-1. View northwest up Napeequa River valley from north of Little Giant Pass [Tsw]. Alluvium of valley bottom (Qa) grades into alluvium (Qu), mostly fans and valley side debris. Napeequa Schist (Kns), with typical relict bedding, dips northeast in foreground canyon wall. The schist is intruded by Cretaceous stitching plutons: the granodiorite High Pass pluton (Kg) and tonalitic stocks (Kt) associated with the Tenpeak pluton. Qcav, rocks of young Cascade volcanoes; Qag, alpine glacial deposits (outwash and debris-flow deposits from the Clark Glacier, out of picture to left).
Qag-1. View southeast along young moraine (Qag) north of Moraine Lake [MBse]. Forbidden Peak (summit at upper center of image) eroded from granodioritic orthogneiss (TKgo). Mount Torment at upper right edge of photo. Photographed in 1987.
Qag-2. View west across Swauk Prairie [Wsw], which is underlain by unit Qag: alpine glacial deposits capped by loess. Miocene flood basalt flows of the Grand Ronde Basalt, Yakima Basalt Subgroup, Columbia River Basalt (Tyg) are tilted up to form Lookout Mountain. Massive landslides (QTl) flank uplifted basalt. Qa, alluvium of valley bottom; Qu, alluvium. Contacts dashed where approximately located and dotted where concealed or hidden from view.
Qag-3. View north from Heliotrope Ridge [MBnw] of Chromatic Moraine (Qag) north of Coleman Glacier, Mount Baker. Ridge behind the moraine is Nooksack Formation (KJn). Photographed in 1967.
Qcav-1. View northeast from northeast side of Glacier Peak volcano [SRse]. An eroded cleaver of Glacier Peak lava (Qcav) stands above an eroded remnant of young moraine (Qag) and older tuff and breccia of Miocene Gamma Ridge caldera (QTcc). These latter deposits are capped by Pleistocene lava (Qcav) which forms Gamma Peak. Photographed in 1961.
Qgf-1. Pleistocene Missoula flood deposits (Qgf) along Columbia River [Cse]. Badger Mountain is dominated by landslides (QTl) from Yakima Basalt flows (Tyg), which partially bury Wenatchee Formation (rocks of the Ohanepecosh episode, Tcao) that overlies Swakane Biotite Gneiss (Kswg). Turtle Rock is a single large block of gneiss within a landslide. A small alluvial fan mapped as Qu is also shown. View southeast from ridge northeast of Swakane Creek. Contacts dashed where approximately located and dotted where concealed..
Qlh-1. View south from point near Gamma Peak [SRse] across bedded lahars (Qlh) from Glacier Peak volcano, out of view to west (right). Foreground exposure is tuffaceous conglomerate capping tuff of Gamma Ridge caldera (QTcc). Tenpeak Mountain on skyline is composed of tonalite and tonalite gneiss (Kt) of the Tenpeak pluton, a Late Cretaceous stitching pluton in the Wenatchee block. Ridge in middle distance is capped with lava from Glacier Peak volcano (Qcav). Photographed in 1961..
Qt-1. Talus (Qt) fringes steep slopes beneath Castle Peak (Eocene granodiorite rocks of late and post-orogenic extension, Tei) and Freezeout Mountain (Three Fools sequence of Haugerud and others (2002), Ktf). Broad floor of Castle Creek valley is covered with glacial drift deposited by the Cordilleran ice sheet (Qga). View west from Mount Winthrop [RMnw].
Qt-2. Talus (Qt) above Silver Lake [MBne]. View northeast to crags of the volcanic rocks of Mount Rahm and beyond to the Hozomeen terrane in the Methow block in Canada. The volcanic rocks of the Ohanapecosh episode of the Cascade Magmatic Arc (Tcao) were intruded by a small ~10 m.y. old pluton, the quartz monzodiorite of Redoubt Creek (Cascade Pass family, QTcp, of the Cascade Magmatic arc). Qag, young alpine glacial moraine. Contacts (thin lines) and fault (heavy line) dashed where approximately located and dotted where concealed.
QTcc-1. View northeast from point south of Ruth Mountain [MBnw] of 4 Ma quartz diorite and quartz monzodiorite of Icy Peak (QTcp) intruding 3.7 Ma rhyolite tuff of Hannegan caldera (QTcc) (Tucker and others, 2007). Contacts dashed where approximately located.
QTcc-2. South side of Hannegan Peak [MBnw] revealing bedded 4.7 Ma rhyolite tuff of caldera fill (QTcc). Granite Mountain to left (northwest) is eroded from the ~30 Ma Baker River Phase (Tcai) of the Chilliwack batholith.
QTcc-3. Hannegan caldera ring fault separates beds of rhyolite tuff (QTcc) on left from Shuksan Greenschist (Kes) on right. View east across upper Crystal Creek [MBnw].
QTcc-4. Rhyolite tuff and breccia (QTcc) that fill Kulshan caldera, upper Swift Creek [MBnw].
QTcp-1. View north up Mineral Creek from Pioneer Ridge. Characteristic glaciated terrain of the Chilliwack batholith, here largely the 6.5 Ma Mineral Mountain pluton (QTcp). Alpine glacial deposits (Qag) floor the Mineral Creek valley [MBne].
QTcp-2. Dark inclusions in quartz monzonite and granite of Nooksack cirque [MBnw], a ~3.4 Ma pluton (QTcp) of the Chilliwack batholith (Tucker and others, 2007).
QTcp-3. Granite of Cascade Pass family (QTcp) on the west wall of Nooksack cirque in foreground. Ruth Mountain [MBnw] to northeast is carved from volcanic breccia of Pliocene Hannegan caldera (QTcc). Both rocks formed in the Cascade Magmatic Arc. Extensive glacial moraine (Qag) covers valley floor. Contact dashed where approximately located. This photo is figure 12 in the accompanying report (sheet 2).
QTl-1. View southeast from ridge northeast of Swakane Creek towards Badger Mountain [Cse], dominated by landslides (QTl) from Yakima Basalt flows (Tyg). Where underlain by weak sedimentary interbeds of the Ellensburg Formation (Te, not visible here), the massive basalt flows commonly collapse into large landslides. Here, landslides partially bury Wenatchee Formation (Ohanepecosh episode, Tcao) that overlies Swakane Biotite Gneiss (Kswg). Turtle Rock is a single large block of gneiss, an erosional remnant of a landslide. Terraces of Pleistocene Missoula flood deposits (Qgf) line the Columbia River. A small alluvial fan mapped as Qu is also shown. Contacts dashed where approximately located and dotted where concealed.
Qu-1. View northwest up Napeequa River valley from north of Little Giant Pass [Tsw]. Alluvium of valley bottom (Qa) grades into alluvium (Qu), mostly fans and valley-side debris. Napeequa Schist (Kns), with typical relict bedding, dips northeast in foreground canyon wall. The schist is intruded by Cretaceous stitching plutons: the granodiorite High Pass pluton (Kg) and tonalitic stocks (Kt) associated with the Tenpeak pluton. Qcav, rocks of young Cascade volcanoes; Qag, alpine glacial deposits (outwash and debris-flow deposits from the Clark Glacier, out of picture to left). Contacts dashed where approximately located and dotted where concealed.
Qvr-1. View north from Wheeler Mountain [SRsw] across North Fork Stillaguamish River valley. Terraces of Vashon recessional outwash deposits (Qvr) and alluvium of valley bottoms (Qa) are prominent. Other rocks and deposits shown, much simplified: QTl, landslide; TKhm, Helena-Haystack mélange; TKeb, eastern mélange belt; Qvt, Vashon till. Devils Mountain fault is south boundary of Darrington-Devils Mountain Fault Zone.
Qvt-1. View north from Wheeler Mountain [SRsw] across North Fork Stillaguamish River valley. Vashon till (Qvt) mantles slopes above terraces of Vashon recessional outwash deposits (Qvr) and alluvium of valley bottoms (Qa) are prominent. Other rocks and deposits shown, much simplified: QTl, landslide; TKhm, Helena-Haystack mélange; TKeb, eastern mélange belt; Devils Mountain fault is south boundary of Darrington-Devils Mountain Fault Zone.
Tcaf-1. View towards west from Keyes Peak of 300-m-high east face of Columbia Peak [SKne]. Miocene breccia of Keyes Peak (volcanic rocks of the Fifes Peak episode, Tcaf) overlies Eocene extensional rocks (Tev) and both are intruded by a small stock of the Grotto batholith (Snoqualmie family of the Cascade Magmatic Arc, Tcas). Contacts dashed where approximately located. Photographed in 1980.
Tcai-1. View north across Berdeen Lake [MBse] to Mount Blum, which is carved from tonalite of Chilliwack batholith (Index family, Tcai, of the Cascade Magmatic Arc) that here intrudes Darrington Phyllite (Ked) of the Northwest Cascade System. Glacial deposits (Qga) are predominently locally derived, but valley was overridden by the Cordilleran Ice Sheet. Photographed 1986.
Tcai-2. Oligocene granodiorite of the Chilliwack batholith (Index family, Tcai) exposed on the ridge west of the upper East Fork of Bacon Creek [MBse]. View northeast to the Northern Picket Range. Glacial erratics on this glacier-smoothed surface at ~2,000 m elevation indicate that the Cordilleran Ice Sheet covered the ridge.
Tcao-1. Monolithologic granitic breccia in Oligocene Big Bosom Buttes caldera (Tcao). Caldera deposits overlie extensional sandstone beds (Tes). View southwest across Silesia Creek. Dashed lines are approximate contacts between geologic units.
Tcao-2. Bedded volcanic breccia and tuff of the Ohanepecosh Formation (Ohanepecosh episode, Tcao), northeast of Howard Hanson Resevoir [SPnw]. Note prominent intraformational unconformity, a common feature in volcanic areas where rapid erosion and deposition are often accompanied by ongoing deformation. Beds beneath this unconformity were deformed (tilted) and beveled by erosion prior to renewed deposition.
Tcas-1. View to northeast from Summit Chief Mountain [SKse]. The Miocene Snoqualmie batholith (of the Snoqualmie family, Tcas) exposed on Mount Hinman has thermally metamorphosed Lower Eocene Swauk Formation (early extensional sedimentary rocks, Tees), which forms resistant crags of Bears Breast Mountain, and the Silver Pass Volcanic Member (Teev), which forms Summit Chief in foreground. Oligocene volcanic rocks of the Ohanepecosh episode (Tcao) forming Mount Daniel have also been recrystallized by heat from the nearby batholith. Contact dashed where approximately located.
Tees-1. Beds of sandstone (Eocene Swauk Formation) in older extensional deposits (Tees) on south side of east ridge of Summit Chief Mountain [SKse]. This photo is figure 13 in the accompanying report (sheet 2).
Tees-2. Coarsely crossbedded fluvial sandstone of the Swauk Formation (early extensional sedimentary rocks, Tees). Note preservation of granitic cobble in pothole, center of image. Goat Mountain area [SPne].
Tei-1. View west from Blackcap Mountain [RMnw] across upper Eureka Creek. In the foreground ridge, thick granite sills of the Eocene Monument Peak stock (Tei) sheath the pluton. They intruded Cretaceous sedimentary rocks of the Pasayten Group (onlap assemblage, Kps). Mount Rolo is rocks of the Three Fools sequence (rocks of the Methow Ocean, Ktf, here the Harts Pass Formation) in the upper plate of the Chuchuwanteen Thrust. Pasayten Group rocks that stratigraphically overlie the Three Fools sequence are visible in Buckskin Ridge across the (hidden) Middle Fork Pasayten River. Contact (thin line) and fault (heavy line) dashed where approximately located and dotted where hidden in this view.
Tei-2. Lineated biotite granite typical of Eocene extensional dikes in Skagit Gneiss Complex. Outcrop in Maselpanik valley, a few miles north of United States-Canada border, northwest of Ross Lake [MBne]. Hand lens cord (about 3 mm diam) for scale.
Tes-1. View northeast from Tronsen Ridge [Wnw]. Timbered hills in the foreground expose early extensional fluvial sandstone and shale of the early and middle Eocene Swauk Formation (Tees). The Leavenworth Fault, hidden in a canyon, separates the Swauk Formation from well-exposed, north- (left-) dipping strata of the middle Eocene Chumstick Formation (Tes) within the Chiwaukum graben. The Entiat Fault, in the distance, separates Chumstick Formation from Swakane Biotite Gneiss (Kswg) and Napeequa Schist (Kns) northeast of the graben. Badger Mountain, far to the east, is Miocene Yakima Basalt (Tyg) that overlies schist, gneiss, Eocene sandstones, and the Entiat Fault. The faults bounding the Chiwaukum Graben are not active; the relief along the scarps mostly reflects differing resistance to erosion of the flanking rocks. Entiat Fault dashed where approximately located and dotted where hidden in this view.
Tes-2. Palmetto leaf fossils in sandstone of extensional deposits (Tes). Sedimentary rocks of the Barlow Pass Volcanics of Vance (1957a,b) (Tev) exposed north of Deer Creek [SRnw].
Tes-3. Basal conglomerate of the Chuckanut Formation (extensional deposits, Tes). Pebbles in the conglomerate are largely vein quartz eroded from nearby Darrington Phyllite (Ked). A locally derived boulder in Clearwater Creek [MBnw].
Tev-1. View east from Stillaguamish Peak [SRse] across minor faults jostling light-colored sandstone interbeds in volcanic rocks of the extensional deposits (Tev; here, the Barlow Pass Volcanics of Vance, 1957a,b). Mount Forgotten is held up by thick dacite dikes associated with the volcanics. Glacier Peak is a Quaternary volcano (Qcav) erupted on older metamorphic rocks of the Wenatchee block. Mount Pugh and ridge to south consist of a tonalite and tonalite gneiss stitching pluton (Kt). Faults dashed where approximately located and dotted where hidden.
Tev-2. View north from upper reaches of South Fork Stillaguamish River [SRse]. On the west side of the canyon are thick beds of fluvial feldspathic sandstone, sedimentary rocks of the extensional deposits (Tes); across the canyon are volcanic rocks of the extensional deposits (Tev). Both sandstone and volcanic rocks are units in the Barlow Pass Volcanics of Vance (1957a,b). A thick rhyolite tuff bed (marked by an arrow) is visible in the volcanic rocks. Recessional outwash deposits (Qvr) of the Vashon stade of Fraser glaciation of Armstrong and others (1965) are visible in the valley bottom.
TKcs-1. Metaconglomerate in Cascade River Schist (TKcs) of the Chelan Mountains terrane. This outcrop showing typical stretched pebbles in the schist is north of Sibley Creek Pass, west of The Trident [MBse], near the outcrop shown in figure 17 (sheet 2).
TKcs-2. Cascade River Schist (TKcs) exposed below the glacier in the Middle Fork Cascade River [SRne], northeast flank of Mount Formidable. Mafic schist contains large flattened clasts derived from volcanic breccia and tuff. Note ice ax, lower right corner, for scale.
TKcs-3. View south from east ridge of Mount Formidable [SRne]. Rocks of the Chelan Mountains terrane, including Cascade River Schist (TKcs), form foreground cliffs. Underlying metamorphosed Marblemount pluton (TKmd) in Old Guard Peak extends along jagged ridge into middle foreground. Sentinel Peak formed of Napeequa Schist (Kns) is cut by the Entiat Fault. These deep-seated metamorphic rocks were partly uplifted, and overlying rocks were eroded, before they were intruded by the Cloudy Pass batholith, a Miocene Cascade Arc pluton (Tcas) that forms Dome Peak and Spire Point in middle background. Further uplift and erosion, especially glacial erosion, preceded eruption of Glacier Peak volcano (Qcav) of the Cascade Magmatic Arc. Contacts (thin lines) and faults (heavy lines) dashed where approximately located and dotted where hidden in this view. This photo is figure 7 in the accompanying report (sheet 2). Photographed in 1958.
TKcs-4. Stretched pebble metaconglomerate in Cascade River Schist (TKcs), western Sisi Ridge [Tnw].
TKeb-1. Pillow structure in amphibolite--metamorphosed basalt--of the eastern mélange belt (TKeb) west of Chair Peak [SPne].
TKeb-2. View east from Mount Index [SKnw] across Skykomish River valley to peaks of Baring Mountain [SKne], erosion-resistant migmatitic gneiss (TKebg) that forms a tectonic slice in less resistant sedimentary rocks of the eastern mélange belt (TKeb). Townsend Mountain and Grotto Mountain are granodiorite of Miocene Grotto batholith (Snoqualmie Family, Tcas), the eroded root of a Cascade Magmatic Arc volcano. Mountains on skyline beyond are carved from rocks of Nason terrane (in Wenatchee block), predominantly Late Cretaceous Chiwaukum Schist (Kncs) and Mount Stuart batholith (Kt). Foreground rock is Jurassic metagabbro, a tectonic slice mixed into western mélange belt (TKwb) in latest Cretaceous or early Tertiary. Tcai, Index batholith (Index family of Cascade Magmatic Arc); Tev, volcanic rocks of extensional deposits; Qa, alluvium of valley floor. Contacts dashed where approximately located and dotted where hidden. This photo is figure 15 in the accompanying report (sheet 2).
TKgo-1. Eldorado Orthogneiss (granodioritic orthogneiss, TKgo) exposed on Forbidden Peak [MBse], viewed from summit ridge of Johannesburg Mountain [SRne] to the southwest. The zig-zag drainage pattern reflects strong jointing in the gneiss. Photographed in 1958.
TKgo-2. Eldorado Orthogneiss (granodioritic orthogneiss, TKgo) containing dark inclusions. Outcrop of this stitching pluton is on south side of West Fork Thunder Creek [MBse].
TKgo-3. View northeast towards Eldorado Peak [MBse] from Sibley Creek Pass, west of The Trident. In foreground, metaconglomerate of middle Eocene to Late Cretaceous Cascade River Schist (TKcs) contains cobbles (deposited in Triassic) stretched to form streaks. Orthogneiss of Eldorado pluton (TKgo) visible in background. Small glaciers and moraine deposits (Qag) in valley are visible behind geologist. This photo is figure 17 in the accompanying report (sheet 2). For a better view of metaconglomerate, see photo TKcs-1. Photographed in 1985.
TKhm-1. Large lumps of erosion-resistant rock dot serpentinite matrix of Helena-Haystack mélange. Most lumps are greenstone (TKhg) or Shuksan Greenschist (Kes). View northwest from ridge southwest of Day Lake [SRnw]. This photo is figure 16 in the accompanying report (sheet 2).
TKmd-1. View northeast from head of Sonny Boy Creek [SRne]. The Entiat Fault separates Marblemount pluton (meta-quartz diorite, TKmd) from Napeequa Schist (Kns). The pluton is overlain by Cascade River Schist (TKcs). The supracrustal rocks were intruded by the Eldorado Orthogneiss (TKgo). Rocks southwest of the fault were metamorphosed in the Cretaceous; metamorphism of rocks to the northeast continued into the Eocene (hence, TKns ). The Miocene Cascade Pass dike (QTcp) intrudes the older rocks. The shallowly intruded dike produced an explosion breccia that crops out on The Triplets. Contacts (thin lines) and faults (heavy lines) dashed where approximately located and dotted where hidden in this view.
TKmd-2. Marblemount meta-quartz diorite (TKmd) on north side of Le Conte Mountain [SRne].
TKmd-3. North face of Bonanza Peak [Tsw], highest nonvolcanic peak in the North Cascade Range at 9,511 ft elevation, viewed from south side of Mount Lyall. The massif is underlain by Marblemount meta-quartz diorite (TKmd). Photographed in 1980.
TKmm-1. Typical Magic Mountain Gneiss (TKmm) exposed on east ridge of Spider Mountain [SRne].
TKmo-1. The southwest side of Elija Ridge, viewed from helicopter near Red Mountain [MBse] to the south, reveals a stack of fault plates. Late Cretaceous and early Tertiary Skagit orthogneiss (TKso) is overlain by probable Napeequa Schist (TKns?) along a low-angle normal fault. A second low-angle normal fault above the schist separates it from metamorphosed rocks of the Methow onlap assemblage (Pasayten Group, TKm), which is overlain by gneissic tonalite (TKto?). Textures within the gneissic tonalite indicate top-to-the south translation. The gneissic tonalite is probably bound by low-angle normal faults. Above the gneissic tonalite is more Napeequa Schist (TKns?), including an ultramafic body (TKnu). At right, a younger high-angle fault juxtaposes these rocks with structurally higher TKm and light-colored metatonalite (TKmo). The anomalous intrusive age of the metatonalite at 103 Ma is discussed in the technical pamphlet. The exposed face is about 3,000 ft (900 m) high. Faults dashed where approximately located.
TKns-1. The southwest side of Elija Ridge, viewed from helicopter near Red Mountain [MBse] to the south, reveals a stack of fault plates. Late Cretaceous and early Tertiary Skagit orthogneiss (TKso) is overlain by probable Napeequa Schist (TKns?) along a low-angle normal fault. A second low-angle normal fault above the schist separates it from metamorphosed rocks of the Methow onlap assemblage (Pasayten Group, TKm), which is overlain by gneissic tonalite (TKto?). Textures within the gneissic tonalite indicate top-to-the south translation. The gneissic tonalite is probably bound by low-angle normal faults. Above the gneissic tonalite is more Napeequa Schist (TKns?), including an ultramafic body (TKnu). At right, a younger high-angle fault juxtaposes these rocks with structurally higher TKm and light-colored metatonalite (TKmo). The anomalous intrusive age of the metatonalite at 103 Ma is discussed in the technical pamphlet. The exposed face is about 3,000 ft (900 m) high. Faults dashed where approximately located.
TKsg-1. Banded gneiss of the Skagit Gneiss Complex (TKsg), included in the stitching plutons. Coarse-grained pegmatite leucosome and late, crosscutting (but lineated) dike are typical of the Skagit Gneiss Complex. Outcrop at head of Torrent Creek [MBne]
TKso-1. The Southern Picket Range [MBne] is eroded from orthogneiss of the Skagit Gneiss Complex (TKso). View south across McMillan Creek from south ridge of Luna Peak. Photographed in 1966.
TKso-2. The Southern Picket Range [MBne] eroded from orthogneiss of the Skagit Gneiss Complex (TKso). Telephoto view northeast from Anderson Butte [MBsw]. Tcai, granodiorite of the Oligocene Chilliwack batholith (Cascade Magmatic Arc, Index family); Tes, sandstone of extensional deposits; Kes, Early Cretaceous Shuksan Greenschist, Shuksan nappe, Easton terrane of the Northwest Cascade System. Names in italics are informal but much used locally. Photographed in 1978.
TKwb-1. Disrupted sandstone, greenstone, and light-colored dikes in argillite matrix, rocks of western mélange belt (TKwb), South Fork Stillaguamish River [SRsw]. This photo is figure 14 in the accompanying report (sheet 2).