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Glacier National Park

Montana · Established May 11, 1910

Billion-year-old seabeds stacked into the Crown of the Continent

Area: 1,013,126 acres
Established: May 11, 1910
Recreation visits: 3,136,557 / yr
State: Montana
Established: May 11, 1910
Area: 1,013,126 acres (4,100 km²)

Glacier Weather Forecast

Loading the National Weather Service forecast for Glacier…

Seven-day outlook at the park's reference point (48.684, -113.801). Elevation changes everything in the mountains — expect colder, windier and wetter conditions on high ground.

Map of Glacier National Park

The Park

Glacier National Park guards a knot of the northern Rockies where the Continental Divide bends through some of the oldest, best-preserved sedimentary rock on Earth. Its peaks are layer cakes of red, green and cream mudstone laid down in shallow seas well over a billion years ago, later shoved eastward over far younger rock and then carved by Ice Age glaciers into horns, cirques and hanging valleys.

Established on May 11, 1910, the park straddles two climates and two worlds. Moist Pacific air nurtures cedar and hemlock forest around Lake McDonald, while dry winds rake the aspen parklands and prairie edges of the east side, where the park meets the Blackfeet Nation. Between them the Going-to-the-Sun Road crosses Logan Pass, and grizzlies, mountain goats and wolverines roam a wilderness shared with Canada's Waterton Lakes.

Geography

The park covers just over a million acres of northwestern Montana, bounded on the north by the Canadian border and on the west by the North Fork of the Flathead River. The Middle Fork of the Flathead River traces its southern edge, and the Blackfeet Indian Reservation forms most of the eastern boundary. Across the border, Waterton Lakes National Park joins it to form the Waterton-Glacier International Peace Park.

Two great ranges, the Livingston and the Lewis, run northwest through the park, and the Continental Divide follows their crest. Six peaks exceed 10,000 ft, led by Mount Cleveland at 10,466 ft. Triple Divide Peak sends its snowmelt toward three oceans by way of the Pacific, Hudson Bay and the Gulf of Mexico. Long glacial lakes fill the valleys; Lake McDonald, the largest, stretches 10 miles and reaches 464 ft deep.

Glaciers gave the park its name, but they are shrinking fast. Roughly 150 glaciers larger than 25 acres existed in the mid-1800s at the close of the Little Ice Age; by 2010 only about 25 of that size remained active.

Landmarks

Mount ClevelandPeak · 10,466 ftThe park's highest summit, rising in the remote north above Waterton Lake.
Logan PassValley · 6,646 ftThe high point of the Going-to-the-Sun Road on the Continental Divide, surrounded by alpine meadows.
Hidden LakeLakeA cirque lake below Bearhat Mountain reached by a boardwalk trail from Logan Pass.
Lake McDonaldLakeThe largest lake in the park, famous for its multicolored stream-worn pebbles.
Saint Mary LakeLakeA windswept east-side lake cradled between peaks at the foot of the Sun Road.
Grinnell GlacierGlacierOne of the park's best-known glaciers, perched below the Garden Wall above Many Glacier.
Sperry GlacierGlacierA shrinking cirque glacier near the historic Sperry Chalet.
Jackson GlacierGlacierVisible from an overlook on the Going-to-the-Sun Road below Mount Jackson.
Swiftcurrent LakeLakeThe heart of the Many Glacier valley, mirroring Grinnell Point.
Iceberg LakeLakeA cirque lake where ice floes often float well into summer beneath sheer walls.
Triple Divide PeakPeak · 8,020 ftIts snowmelt drains to the Pacific, Hudson Bay and the Gulf of Mexico.
Chief MountainPeakA detached block of ancient rock at the eastern front, sacred to the Blackfeet and a textbook remnant of the Lewis Overthrust.
Mount SiyehPeakOne of the park's six 10,000-foot peaks, with a colossal north face above Cracker Lake.
Heavens PeakPeakA snowy pyramid dominating the view west from the Sun Road's upper switchbacks.
Kintla LakeLakeA remote lake at the end of the rough road through the park's northwestern corner.
Two MedicineValleyA quiet southeastern valley of lakes held sacred in Blackfeet tradition.

Geology

Most of the rock in Glacier began as mud, sand and lime settling into a vast shallow sea roughly 1.5 billion years ago. Over hundreds of millions of years these sediments piled up into the Belt Supergroup, a sequence of argillite, quartzite, limestone and dolomite so little altered that ripple marks, mud cracks and raindrop prints still survive. Colonies of blue-green microbes built mounded stromatolites in the warm shallows, making the park one of the world's richest records of early life.

About 780 million years ago molten rock squeezed between layers of the Siyeh Limestone and cooled into the Purcell Sill, a dark band of diorite about 100 ft thick that bakes the limestone above and below it into white marble. Today the sill runs like a pencil line across cliffs throughout the park.

From roughly 150 to 60 million years ago, the forces that raised the Rocky Mountains pushed a slab of Belt rock several miles thick eastward along the Lewis Overthrust, sliding it some 50 miles over much younger Cretaceous rock. Erosion has since isolated pieces of the slab, and Chief Mountain stands as a lone outlier of billion-year-old rock resting on beds hundreds of millions of years younger.

Beginning around 2 million years ago, repeated ice ages buried the ranges beneath glaciers that scooped out the long valley lakes, sharpened the peaks into horns and arêtes and left hanging valleys spilling waterfalls. The small glaciers now vanishing from the cirques are not remnants of that great ice but products of the much later Little Ice Age.

Deep time

About 1.5 billion years agoSediments began accumulating in the shallow Belt sea that would become the park's layered peaks.
About 1.44 billion years agoStromatolite-building microbes flourished in warm, shallow water, leaving fossils now seen along the Sun Road.
About 780 million years agoMagma intruded the Siyeh Limestone to form the dark Purcell Sill.
About 150 to 60 million years agoMountain building thrust Belt rock roughly 50 miles east along the Lewis Overthrust.
About 2 million years agoIce ages began, sending glaciers down the valleys to carve lakes, cirques and horns.
About 1550 to 1850The Little Ice Age grew the small cirque glaciers that are now rapidly melting.

The rocks

Belt SupergroupMesoproterozoic
The thick stack of sedimentary rock that makes up nearly all of the park's mountains.
Altyn FormationMesoproterozoic
Pale dolomite and limestone forming the lowest Belt cliffs on the east side.
Appekunny FormationMesoproterozoic
Green argillite colored by iron that was deposited without oxygen.
Grinnell FormationMesoproterozoic
Brick-red argillite marked with ripple marks and mud cracks from tidal flats.
Siyeh Limestone (Helena Formation)Mesoproterozoic
Thick gray limestone that holds the park's stromatolites and hosts the Purcell Sill.
Purcell SillAbout 780 million years old
A roughly 100-foot band of dark diorite with white marble margins.
Cretaceous shale beneath the Lewis OverthrustCretaceous
Soft, young rock over which the ancient Belt slab slid.

Trees, Plants & Ecosystems

1,171vascular plant species recorded

Western cedar-hemlock forestWest-side valleys such as Lake McDonald
A Pacific-influenced forest of western red cedar and western hemlock, with devil's club and ferns in the damp understory.
Montane conifer forestLower slopes on both sides of the Divide
Lodgepole pine, western larch and Douglas fir shaped by frequent fire.
East-side aspen parkland and prairieEastern valleys and mountain front
Aspen groves, rough fescue grassland and wind-shaped limber pine where the Rockies meet the Great Plains.
Subalpine forest and meadowUpper slopes below treeline
Subalpine fir, Engelmann spruce and whitebark pine interspersed with beargrass and glacier lily meadows.
Alpine tundraAbove treeline, including Logan Pass
Snow-packed rock and cushion plants grazed by mountain goats, marmots and ptarmigan.

Trees

Western red cedarThuja plicataCenturies-old cedars shade the Trail of the Cedars, near the eastern limit of their range.
Western hemlockTsuga heterophyllaA shade-loving partner of cedar in the wettest west-side forests.
Western larchLarix occidentalisA fire-resistant conifer that turns gold and drops its needles each autumn.
Subalpine larchLarix lyalliiA hardy larch of high rocky slopes near treeline.
Whitebark pinePinus albicaulisA keystone high-elevation pine whose seeds feed nutcrackers and bears, declining from blister rust.
Lodgepole pinePinus contorta var. latifoliaRegenerates in dense stands after fire.
Douglas firPseudotsuga menziesii var. glaucaA thick-barked tree of dry, warm montane slopes.
Engelmann sprucePicea engelmanniiA dominant subalpine spruce of cold, moist sites.
Subalpine firAbies lasiocarpaA spire-shaped fir that forms krummholz mats at treeline.
Ponderosa pinePinus ponderosa var. ponderosaScattered on warm, dry sites on the west side.
Quaking aspenPopulus tremuloidesIts groves brighten the east-side parklands in autumn.
Black cottonwoodPopulus balsamifera ssp. trichocarpaTall trees of river bottoms and floodplains.

Wildflowers, shrubs & other plants

BeargrassXerophyllum tenaxTall creamy plumes of this lily relative bloom in massive displays every few years.
Glacier lilyErythronium grandiflorumYellow nodding flowers that burst up at the edges of melting snowbanks.
BitterrootLewisia redivivaMontana's state flower, a pink rosette of dry, rocky ground.
Fairy slipperCalypso bulbosaA small pink orchid of shaded coniferous forest.
Queen's cupClintonia unifloraA single white lily-like flower followed by one blue berry.
Pink mountain-heatherPhyllodoce empetriformisRosy bells cover subalpine slopes near Logan Pass.
Red monkeyflowerMimulus lewisiiBrilliant magenta blooms line alpine seeps and stream banks.
Scarlet paintbrushCastilleja miniataA partially parasitic wildflower that paints meadows red.
Alpine dryadDryas octopetalaA mat-forming white-flowered plant of limestone ridges.
Moss campionSilene acaulisA pink cushion plant that can take decades to grow a few inches.
Sky pilotPolemonium viscosumMusky-scented blue flowers on high rocky talus.
Tall huckleberryVaccinium membranaceumThe late-summer berry crop that grizzlies depend on before hibernation.
Devil's clubOplopanax horridusA spiny shrub of wet west-side forest, a sign of Pacific influence.
Arrowleaf balsamrootBalsamorhiza sagittataBig yellow sunflowers on dry east-side slopes in early summer.

Wildlife

59mammals
242birds
3reptiles
6amphibians
26fish

Mammals

Grizzly bearUrsus arctos horribilisGlacier supports one of the densest grizzly populations in the lower 48 states.
Black bearUrsus americanusMore common in forested valleys, with coats from black to cinnamon.
Mountain goatOreamnos americanusThe park's emblem, often seen at Logan Pass and Hidden Lake.
Bighorn sheepOvis canadensisRams graze east-side slopes around Many Glacier.
Gray wolfCanis lupusPacks roam the park, especially the remote North Fork valley along the Canadian border.
WolverineGulo guloDepends on deep spring snowpack for denning in high country.
Canada lynxLynx canadensisA secretive forest cat that hunts snowshoe hares.
Hoary marmotMarmota caligataA large marmot whose shrill whistles echo across alpine meadows.
American pikaOchotona princepsGathers haypiles in talus and is sensitive to warming summers.
MooseAlces alcesFeeds in lake shallows and willow marshes.
ElkCervus elaphusWinters on lower slopes and bugles in September meadows.
American martenMartes americanaA tree-climbing weasel of mature conifer forest.
BeaverCastor canadensisEngineers ponds along slow valley streams.
Columbian ground squirrelSpermophilus columbianusChirps from meadows and spends much of the year hibernating.

Birds

Harlequin duckHistrionicus histrionicusBreeds on rushing streams such as McDonald Creek before returning to the sea.
White-tailed ptarmiganLagopus leucurusAn alpine grouse that stays year-round, white in winter and mottled in summer.
Clark's nutcrackerNucifraga columbianaCaches thousands of whitebark pine seeds and plants new trees in the process.
American dipperCinclus mexicanusWalks underwater along stream bottoms hunting insect larvae.
Golden eagleAquila chrysaetosMigrates in large numbers along the mountain front each autumn.
Bald eagleHaliaeetus leucocephalusFishes the park's large lakes and rivers.
OspreyPandion haliaetusNests atop snags beside lakes and dives feet-first for fish.
Common loonGavia immerA sensitive breeder on quiet west-side lakes.
Black-backed woodpeckerPicoides arcticusMoves into recently burned forest to feed on wood-boring beetles.
Pileated woodpeckerDryocopus pileatusA crow-sized woodpecker of old cedar and cottonwood stands.
Rosy-finchLeucosticte arctoaForages along melting snowfields on the highest ridges.
Steller's jayCyanocitta stelleriA crested blue jay of the western forests.
Gray jayPerisoreus canadensisA fearless subalpine resident known for approaching picnickers.

Reptiles & amphibians

Rocky Mountain tailed frogAscaphus montanusLives in cold, fast streams and has an unusual tail-like mating organ.
Columbia spotted frogRana luteiventrisCommon in ponds and marshes, with a salmon-colored belly.
Long-toed salamanderAmbystoma macrodactylumA dark salamander with a yellow-green back stripe that breeds in snowmelt ponds.
Western toadBufo boreasMass-migrates between breeding ponds and uplands.
Boreal chorus frogPseudacris maculataIts trilling calls fill wetlands in spring.
Painted turtleChrysemys pictaBasks in low-elevation ponds and is one of only three reptiles on the park checklist.
Common garter snakeThamnophis sirtalisHunts frogs and fish along wetland edges.
Terrestrial garter snakeThamnophis elegansA widespread snake of meadows and forest openings.

Fish

Bull troutSalvelinus confluentusA threatened native char that needs cold, clean water.
Westslope cutthroat troutOncorhynchus clarkii lewisiA native trout threatened by hybridization with rainbow trout.
Lake troutSalvelinus namaycushNative east of the Divide but an invasive predator in several west-side lakes.
Arctic graylingThymallus arcticusA sail-finned fish of a few high lakes.
Mountain whitefishProsopium williamsoniA native bottom-feeder common in the Flathead rivers.

Species totals are the park's certified NPSpecies checklist (occurrence: present).

Climate & When to Visit

Glacier straddles the Continental Divide, and the Divide splits its weather. Warm, moist Pacific air flows in from the west and drops its moisture on the western slopes, feeding lush forest and deep snowpack. From the northeast, cold, dry Arctic air spills across the plains and slams against the mountain front. Where the two air masses meet along the Divide, weather can turn from sunshine to sleet in an hour.

Elevation adds its own layer. Valleys can be warm and sunny while Logan Pass, more than 3,000 ft higher than Lake McDonald, sits in cloud, wind and snow. Winters are long and snowy, and the east side is notorious for fierce chinook and downslope winds. Snow can fall in the high country in any month, and the alpine section of the Going-to-the-Sun Road typically opens only in late June or July after crews clear deep drifts.

Spring
April through June is a mix of rain in the valleys and heavy snow above. Lower trails melt out first while high roads and passes stay buried.
Summer
July and August bring warm valley days and cool nights, with afternoon thunderstorms over the peaks. This is the only reliable window for the full Going-to-the-Sun Road and high-country trails.
Autumn
September offers crisp air, golden larch and aspen, and fewer crowds. Early snowstorms can close high roads by October.
Winter
Deep snow and frigid temperatures, with Arctic outbreaks on the east side and heavy snow on the west. Much of the park is reachable only by ski or snowshoe.

Weather hazards

Sudden mountain storms: Carry rain gear and warm layers on every hike, because summer thunderstorms and snow squalls build quickly along the Divide.
Lightning: Leave exposed ridges and passes like Logan Pass before afternoon storms arrive.
High winds: East-side gusts can be violent enough to knock hikers off balance, so use care on exposed trails.
Snowfields and avalanches: Steep, icy snow lingers on trails into summer, and avalanche danger is serious in winter and spring.
Cold, swift water: Glacier-fed streams and lakes are frigid, and slick rocks along their banks cause many accidents.

Glacier Questions

When is the best time to visit Glacier National Park?

Mid-July through mid-September is the best time for most visitors, since that is when the entire Going-to-the-Sun Road and most high trails are usually open. Late June can be lovely at low elevations, and September brings golden larches with fewer crowds.

What is the weather like at Logan Pass?

Logan Pass sits at 6,646 ft on the Continental Divide and is usually much cooler and windier than the valleys. Snow can linger into July and fall again by September, and afternoon thunderstorms are common in summer.

Are there still glaciers in Glacier National Park?

Yes, but far fewer than there once were. About 150 glaciers larger than 25 acres existed in the mid-1800s, and by 2010 only about 25 remained active. Grinnell, Sperry and Jackson glaciers are among those still visible.

Where can I see wildlife?

Mountain goats and bighorn sheep are often seen around Logan Pass, Hidden Lake and Many Glacier. Many Glacier is also one of the best areas to glass slopes for grizzly bears, and moose frequent marshy lake edges in the early morning.

Why are the rocks in Glacier red and green?

Glacier's peaks are built from Belt Supergroup sediments laid down roughly 1.5 billion years ago. Iron in the mud turned red where it was exposed to oxygen on tidal flats, as in the Grinnell Formation, and green where it was buried without oxygen, as in the Appekunny Formation.

What is the Lewis Overthrust?

The Lewis Overthrust is a great fault along which a slab of billion-year-old rock slid about 50 miles east over much younger Cretaceous rock during Rocky Mountain building. Chief Mountain, at the park's eastern edge, is an isolated block of that ancient slab.

More parks in the Rocky Mountains

← Gateway Arch National Park Glacier Bay National Park & Preserve →

Sources: www.nps.gov · www.nps.gov · www.nps.gov · irmaservices.nps.gov · en.wikipedia.org · Official NPS site