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Welcome to the audio-described version of the Ice Age Floods National Geologic Trail's official print brochure. Through text and audio descriptions of photos, illustrations, and maps, this version interprets the two-sided color brochure that Ice Age Floods National Geologic Trail visitors receive. The brochure explores the history of the park, some of its highlights, and information for planning your visit. This audio version lasts about 20 minutes which we have divided into 13 sections, some with additional subsections, as a way to improve the listening experience.
Sections 1 to 3, counting this description as 1, give an overview of the trail and the front side of the brochure. Sections 4 to 9 cover the front side of the brochure, with includes information on the history of the floods, the first scientists to study the floods, and key sites where evidence of the floods can be seen. Section 10 gives an overview of the back side of the brochure. Sections 11, 12, and 13 cover the back side of the brochure in detail, including the full spread map that takes up the majority of this side of the brochure. Section 14 gives further details on accessibility considerations when visiting the Ice Age Floods National Geologic Trail.
This brochure provides a detailed map of the Ice Age Floods Geologic Trail, a National Park Site that spans Montana, Idaho, Washington, and Oregon. This site is a driving trail not boundary owned by the Park Service, but in partnership with other federal, state, local, and private partners. The front side of the brochure shows pictures of suggested features found along the trail with deeper descriptions of the individual features and how they relate to the Ice Age story. It also overviews how scientists have drastically changed their theories of the landscape, the scientists involved, and the understanding of the current theory of the Ice Age Floods. The back side of the brochure is composed of a large map panning Montana, Idaho, Oregon, and Washington using different colors to show Main Ice Age Floods National Geologic Trail Route, Loop & Spur Trail Route, Ancient Glacial Lakes, and Area Impacted by Ice Age Flooding. It includes the main modern features, main ancient features, regulations, and website services. To find out more about what resources might be available or to contact the park directly, visit the "Accessibility" and "More Information" sections at the end of this audio-described brochure.
The front side of the brochure orients visitors to the Ice Age Floods National Geologic Trail, the story that resulted in the trail in the Pacific Northwest, and the lasting impressions that remain today. This side contains a mix of park photos, illustrations, and text. The top of the page is taken up by a collage of five color photos representing different Ice Age Floods geologic features. Below this line of photos and to the left is a description of the flood’s impacts on the landscape during the last ice age. To the right is information on the two men instrumental in solving the mystery of the ice age floods in the Pacific Northwest. The bottom half of the front page lists the 13 locations found on the map that people can visit to learn more about the effects of the ice age floods on the landscape. Each location has a picture attached.
Image 1 of 5: An erratic on Rattlesnake Mountain
DESCRIBING: A square color photograph.
SYNOPSIS: A large gray boulder sits in the foreground of a grassy field. In the background are hills and ridges rising to a small mountain peak. There are no other gray rocks anywhere in the field, showing how unusual the large boulder’s location is.
IN-DEPTH DESCRIPTION: The angular boulder is weathered, cross-cut by fractures and veins that have been deepened and evacuated over time. Part of the boulder is buried below the sandy ground. Bunches of green-yellow grass and the occasional white wildflowers surround the boulder. The same partially grassy surface extends in the distance to a series of low, undulating ridges. Beyond the ridges, the ground stays the same yellowish color but rises to a clear single peak. The peak is slightly darker and in the shadow of a cloud. The sky is mostly cloudy with areas of patchy blue sky.
CAPTION: An erratic on Rattlesnake Mountain
CREDIT: BRUCE BJORNSTAD
Image 2 of 5: Palouse Hills
DESCRIBING: A vertical rectangular color photograph.
SYNOPSIS: An aerial view of grassy hills that ripple like waves through the landscape. The hills have no vegetation other than grass, showing the topography very clearly. The grass varies in color from bright green to muted green to tan.
IN-DEPTH DESCRIPTION: The hills take up the entirety of the photo, making for a dramatic and expansive scene. The closest hill is a field of emerald green, while the next is mostly brown with only a thin covering of green, while the next is almost completely brown. This patchwork of color continues even into the furthest hills in the photo. Low points in the landscape are in shadow while high points are lit, making for an interplay of light and color across the altogether unusual scene. The wave patterns are irregular, never exactly repeating, but the smooth landscape portrays a sense of calm. Scale is different to gauge, but a dirt road winds its way like twine down the side of the closest hill, giving the impression we may be looking at several miles of landscape.
CAPTION: Palouse Hills
CREDIT: BRUCE BJORNSTAD
Image 3 of 5: Frenchman Coulee
DESCRIBING: A horizontal rectangular color photograph.
SYNOPSIS: An expanse of 300-foot-high rocky cliffs stretches into the distance of a desert landscape. Vertical columns dominate the top of the cliff, with a slope of loose rocks at the base. The light of late day hits the cliff face, giving the rocks a warm earthly glow and casting long shadows on the surrounding landscape.
IN-DEPTH DESCRIPTION: The cliffs appear to form a curved arc and the photo has been taken from one end of this curve looking across to the far end of the cliffs. In the foreground sit two blue-green sagebrush bushes close to the ground, surrounded by patchy green ground and bunches of yellow grasses. Light hits a rock outcrop on the lefthand side of the image, which we can infer to be the same type of rock as the cliffs in the distance. The rock is rough and breaking into smaller pieces, covered in black and white spots of lichen and weathering. The cliffs across the way are similar in character and color, but from this distance the vertical columns formed by the rock are apparent. From this distance, they almost look like a line of toothpicks forming the top of the cliff, below which there are piles of loose material where rocks have eroded off the cliffs. The ground beneath the cliffs has small dots indicating bushes, which are more concentrated in some areas than in others. On top of the cliffs, in the distance there is a small hill covered in a white substance. Beyond is a tall ridge with a cellphone tower on it.
CAPTION: Frenchman Coulee
CREDIT: BRUCE BJORNSTAD
Image 4 of 5: Rhythmites at White Bluffs
DESCRIBING: A vertical rectangular color photograph.
SYNOPSIS: Close up on tiers of white rock rising in layers on a steep cliff side. Sparse vegetation grows on pale rocky rubble on shallow shelfs between the layers.
IN-DEPTH DESCRIPTION: The rock layers alternate between bands of thick white layers and thin grey layers. The thick white layers are more resistant to erosion and stick out further, whereas the grey layers are softer and contain loose sediment that has eroded out. There is a clear repeating pattern of the thick and thin layers, and while only five sets of these thick and thin layers are visible, we can see that more layers continue below, out of the frame. A few green, fuzzy plants dot the lower rock layers, however it is it hard to tell exactly what kind of plants or their size, giving very little sense of scale in the photo.
CAPTION: Rhythmites at White Bluffs
CREDIT: BRUCE BJORNSTAD
Image 5 of 5: West Bar Giant Current Ripples
DESCRIBING: A square color photograph.
SYNOPSIS: An open desert-like landscape with little vegetation shows rippling topography. A long body of water is seen in the distance on the left, with sloping rocky cliffs in the distance to the right. A narrow dirt road winds through the landscape towards a small building in the distance.
IN-DEPTH DESCRIPTION: Light hits the landscape at a low angle, emphasizing the ridges of the ripples. The ripples are like the ones you might find on the beach or in a stream, with long undulating ridges that are roughly the same height and run more or less parallel to each other and the viewer. However, the road that cuts perpendicular across these ridges tells us that these ridges are much larger than those you would find anywhere else. The building next to the road is dwarfed by the ripples next to it. In the distance, the sloping rocky cliffs stand taller than ripples, indicating that the ripples formed in a low spot in the landscape. These cliffs are half in shadow and half in light, and the water we can barely make out in the distance is in shadow.
CAPTION: West Bar Giant Current Ripples
CREDIT: BRUCE BJORNSTAD
Floods of Change
One of the greatest stories of ancient North America is written in the rocks and sediments of the Pacific Northwest. Massive floods swept across parts of Montana, Idaho, Washington, and Oregon, sculpting and changing the landscape, leaving clues for scientists and travelers to unravel. Explore the geologic evidence left behind as you travel the Ice Age Floods National Geologic Trail.
Around 18,000 years ago an advancing glacial lobe blocked the Clark Fork River in current-day northern Idaho. Behind this giant ice dam, water rose 2,000 feet (610 m) filling the valleys to the east, creating Glacial Lake Missoula. As the ice lobe retreated, pressure from the lake caused the ice dam to fail, releasing up to 600 cubic miles (~2,500 km³) of water, the volume of Lake Ontario and Lake Erie combined, in as little as two days. This wall of water, ice, and debris hundreds of feet tall raced westward over 16,000 square miles (41,440 km2) through present-day Montana, Idaho, Washington, and Oregon.
Over the course of the next 3,000 years, the glacial lobe continued the cycle of advancing, blocking the Clark Fork River, filling Glacial Lake Missoula, and then failing, releasing the water across the landscape. Over time, dozens of floods left a lasting change on the natural environment and human habitation in the region.
These glaciers and floods scoured all evidence of humans from this ancient landscape, leaving us with stories passed down by the American Indian tribes that have called this region home for the last 15,000 years. Their cultural and spiritual traditions are deeply tied to these lands, the powerful forces that created them, and that continue to shape their modern way of life.
Widespread reminders of the Ice Age Floods are scattered throughout the area. Drive the trail and make your own connections with gigantic basalt coulees and dry waterfalls, house-sized boulders moved by ice and water, ancient lake shores etched in hillsides, and huge ripple marks taller than your car.
The story of the Ice Age Floods took nearly 50 years to piece together. During the 1920s–40s, geologists debated the origin of eastern Washington’s Channeled Scabland where eroded volcanic basalt surrounds braided channels and coulees. Most geologists believed that the Channeled Scabland was made by slow erosion by glaciers and streams. Geologic evidence that didn’t fit with this idea led geologist J Harlen Bretz to hypothesize that the Channeled Scabland was formed by a catastrophic flood. Initially ridiculed, Bretz’s hypothesis was validated when new technologies like satellite photography provided supporting evidence. By the late 1970s it was universally accepted that the scoured landscape of the northwestern United States was the result of multiple Ice Age Floods.
DESCRIBING: Black and white photo of J Harlen Bretz.
SYNOPSIS: Black and white photo of an elderly white man seen in half-profile from the chest up.
IN-DEPTH DESCRIPTION: J. Harlen Bretz is seen in half-profile. He has fine creases around his eyes and deep furrows around his mouth. He’s smiling slightly, his eyes squinted a little behind a pair of oval-shaped spectacles with wire-rim frames. He appears to be tanned, his skin nearly matching the shade of his collared, button-up shirt. On his head he wears a hardhat that casts a dark shadow across the top of his face. Behind him, one sees the blurry outlines of a rocky slope.
CAPTION: J Harlen Bretz
CREDIT: JULIAN GOLDSMITH
RELATED TEXT: J Harlen Bretz, 1882-1981
A high school teacher turned geology professor, J Harlen Bretz was fascinated with the glacial geology of the Puget Sound. He became an expert on the features of stream and glacial erosion and began field research in the Channeled Scabland of eastern Washington in 1922. Challenging common beliefs, Bretz believed that the Channeled Scabland was formed not by ordinary stream erosion but by a catastrophic flood. What eluded him, though, was the source of the floods.
DESCRIBING: Black and white photo of a of Joseph Pardee.
SYNOPSIS: Black and white photo of a young, white man’s left profile from his shoulders up. He has a straight face as he looks off to the left. His hair is short and parted in the middle. He wears a white collar under a black shirt. The background behind him is gray.
IN-DEPTH DESCRIPTION:
Joseph Pardee is seen in half profile from the chest up. He is looking off into the distance to the left of the camera with a stern facial expression. He has dark eyes and dark eyebrows, and his light-colored hair is kept short and parted in the middle. The collar of his white shirt is stiff and buttoned high on his neck, and he wears a crisp dark tie. He wears a dark suit jacket over his shirt. Behind him is a featureless gray background.
CAPTION: Joseph Pardee
CREDIT: USGS
RELATED TEXT: Joesph Pardee, 1871-1960
Joseph Pardee, a geologist with the US Geological Survey, proposed a source for Bretz’s catastrophic floods. As he studied the intermontane basins of Montana in 1910, he found high water marks near Missoula, Montana—evidence of a large glacial lake. Later, in the Camas Prairie of northwestern Montana, he discovered giant ripple marks of sediment made by powerful currents flowing over the bottom of ancient glacial Lake Missoula. Like Bretz, Pardee’s discoveries played a key role in understanding the story of the Ice Age Floods. It was not until the late 1970’s that geologists began to generally agree on the idea that multiple floods were a key part of this story.
The work of these and present-day scientists show us that the gradual processes shaping our Earth can be accentuated by sudden cataclysmic geologic events, and that such events are possible in our lifetimes!
QUOTE: "The magnitude of the erosive changes wrought by these glacial streams is nothing short of amazing." – J Harlen Bretz, 1923
TEXT: Lasting Impressions
As the Ice Age Floods swept across the landscape from present-day Montana to the Pacific Ocean, they eroded massive amounts of rock and debris from the land and deposited them farther down the flood route. Along the National Geologic Trail, deeply eroded coulees, scoured water gaps, remnant waterfalls, and basalt cliffs lead to gravel bars, giant ripple marks, and large boulders. These clues from the past guide your passage through geologic time and space.
Of the thousands of large flood features that decorate the landscape of the Northwest US, thirteen are featured here to help explain the story. Find them on the map side of this brochure marked by numbered callouts.
DESCRIBING: A vertical rectangular color photograph.
SYNOPSIS: Shown from an aerial perspective, a hill dominates the image. It has multiple horizontal lines that stretch from one side of the hill to the other. These lines, which are actually the residual evidence of falling and rising water levels, show up as red-brown stripes interspersed with green. Hazy blue mountains can be seen in the background.
IN-DEPTH DESCRIPTION: The rounded hill in the foreground is speckled in reds and greens of grasses and low shrubs. Ancient shorelines from Glacial Lake Missoula appear as horizontal lines that stretch along the sides of the hill, whose name is Mount Jumbo. At least twenty shoreline marks are visible, with the highest one occurring near the top of the hill. On the left flank of the hill, one sees a bright white “L” with a trail that zig zags between the L and the valley floor. Patches of dark green forest grow near the crown of the hill, with a mountain range visible just beyond that. The mountains appear dark green with patches of forest and grass. The cloudy sky above casts a slight blue hue onto the ridged landscape.
CREDIT: Bruce Bjornstad
RELATED TEXT: Imagine you are standing on the edge of glacial Lake Missoula 15,000 years ago. You can hear lapping waves cutting benches known as “strandlines” into the shoreline. Today, you can see these huge strandlines on hills surrounding Missoula, Montana, marking changes in lake level over time. On Mount Sentinel, marked with an “M”, and Mount Jumbo, marked with an “L”, the strandlines are seen as horizontal lines in the vegetation or highlighted by snow in the winter. Public hiking trails switchback through the strandlines on Mount Sentinel and Mount Jumbo.
DESCRIBING: A vertical rectangular color photograph.
SYNOPSIS: An aerial view of a grassy field with rippling hills that stretch into the distance. A small farmhouse and shed sit in the foreground under trees with yellow leaves. In the distance are mountains with some snow.
IN-DEPTH DESCRIPTION:
The image is dominated by a view of green hills that undulate like waves to the horizon. A farmhouse can be seen in the foreground, though it is mostly obscured by two tall, leafless trees. A shed sits near the farmhouse under several shorter trees with bright yellow leaves. Farther in the distance, the hills flatten into an open plain without any discernable vegetation, and beyond that, taller hills and snow-capped mountains rise up.
CREDIT: Dave Bennet
DESCRIBING: A vertical rectangular color photograph.
SYNOPSIS: A teal blue river cuts through the landscape with steep tree covered cliffs to the left and flat green plains to the right. Roads run parallel to the river, to the right of the green fields. Beyond the river, grey clouds loom in a pale blue sky.
IN-DEPTH DESCRIPTION: This image provides an arial view of the landscape, featuring mountains and a river on the left, and grassy green fields on the right. The mountains have exposed cliffs of purple-grey rocks. A pile of rubble sits at the base of the cliffs, forming a gentle slope. Pine trees grow at the top of several mountain ridges and at the base of the cliffs near the river. Pale teal in color, the river sweeps from left to right and disappears into the mountains at the horizon. The river has a single shallow island, which can be seen near the left shoreline. Dark bushes and trees grow at the edge of the field, which seems to drop off sharply at the river shore. The rest of the field is covered with grass and stretches into the distance in a long strip. Several small red barns sit together in the foreground, near the river. A strip of railroad tracks and a narrow two-lane road runs parallel to the river on the far right of the field and stretch into the distance. More mountains are seen at the horizon. Some peaks look similar to the purple-grey cliffs on the left of the picture, while others in the far distance seem taller and more vegetated. The distant mountains are partly shadowed by puffy grey and white clouds.
CREDIT: Bruce Bjornstad
RELATED TEXT: West of the Camas Prairie Ripples is a flume-shaped section of canyon called the Eddy Narrows. Draining glacial Lake Missoula waters discharged at a rate of 15 million cubic meters per second, scouring the valley walls down to bare bedrock up to 1,000 feet (305 m) above the valley floor. On Montana Highway 200, between mileposts 59 and 60, stop at the KooKooSint Bighorn Sheep Viewing Interpretive Site to see these vertical canyon walls.
DESCRIBING: A vertical rectangular color photo.
SYNOPSIS: Forested mountains tower over a dark lake that reflects the sky above.
IN-DEPTH DESCRIPTION: A lake dominates this image, with mountain ranges surrounding it on two sides. The mountains to the right are dark green while the snow-capped peaks straight ahead are partially obscured by fog. The water in the lake is smooth and calm, partially reflecting the pale blue sky above. Misty tendrils lie over the water.
CREDIT: Bruce Bjornstad
RELATED TEXT: As the Purcell Trench ice lobe of the Cordilleran Ice Sheet advanced south from Canada, it was stopped by the Green Monarch Ridge, building an ice dam 4,000 feet (1219 m) tall and nearly 40 miles (64 km) wide that blocked the Clark Fork River, thus filling glacial Lake Missoula. View the Green Monarch Ridge and the Purcell Trench from a large pullout on Idaho State Route 200, about one mile (1.6 km) west of Hope, Idaho and 15 miles (24 km) east of Sandpoint, Idaho.
DESCRIBING: A vertical rectangular color photograph
SYNOPSIS: This aerial image shows green forests stretching across a flat landscape to the mountains in the distance.
IN-DEPTH DESCRIPTION: Green forest covers a flat landscape stretching up to mountains in the distance. To the left, a dark blue lake lies below a forested ridge. To the right, the trees taper off, replaced by grassy terrain with roads cutting through the landscape. Pockets of grass show through the trees across the image. A cloudy blue sky hovers above the mountains at the horizon.
CREDIT: Bruce Bjornstad
RELATED TEXT: When the ice dam holding back glacial Lake Missoula burst, water was not the only thing to rocket through the breach. Ice, boulders, and other debris were deposited in the Rathdrum Prairie by escaping floodwaters. Explore this and other flood remnants like debris-dammed lakes, giant ice-rafted boulders and erratics, and huge gravel bars at Farragut State Park on the southern tip of Lake Pend Oreille, Idaho.
DESCRIBING: A vertical rectangular color photograph.
SYNOPSIS: A riverbed framed by large basalt boulders.
IN-DEPTH DESCRIPTION: Water rushes away from the viewer, flowing around and over shallow rocks in a riverbed. White water appears downstream, showing the direction of the river’s flow. Basalt boulders as large as houses frame the river on either side. These remnants from ancient lava flows are grey in color with rough sides and edges. The water in this image flows past a third basalt boulder and toward a pine forest that covers the distant hillside. The sky above is clear and blue.
CREDIT: NPS Justin Radford
RELATED TEXT: As floodwaters flowed west, they scoured and displaced an enormous amount of soil and material. Sand from the bed of Lake Pend Oreille once filled the Spokane River drainage. Visit the Bowl, a circular depression in the Spokane River likely caused by a kolk vortex similar to an underwater tornado, and Pitcher, a detached block of basalt, at Riverside State Park just outside of Spokane, Washington. From here floods waters rushed out across Washington State creating the Channeled Scabland.
DESCRIBING: A horizontal rectangular color photograph.
SYNOPSIS: This image shows the cliffs left by a former waterfall. A double rainbow stretches above the scene and into the sky above.
IN-DEPTH DESCRIPTION: A former waterfall has left behind a sharp cliff-face shaded tan and black. Talus slopes start about halfway up the cliffs, which tower over a lake at the bottom. Sunlight casts a golden hue onto the cliffs at the right, leaving the left side of the image in shadow. A double rainbow juts straight up from the top of the cliff and into the sky. The rainbow on the right is bright and clear while the one on the left appears like a faint echo. The sky has a mix of white and grey clouds with streams of light shining between them.
CREDIT: Bruce Bjornstad
RELATED TEXT: In eastern Washington, The Okanogan lobe of the Cordilleran ice sheet diverted the Columbia River south along the path of the Grand Coulee. During the floods, water hundreds of feet deep eroded the canyon upstream forming a huge waterfall. The recession of the waterfall’s lip during each flood event carved a canyon 18 miles (29 km) upstream from the fall’s original location at Soap Lake. A huge “dry waterfall” remains as an unmistakable clue of the floods’ power. Four times larger than Niagara Falls, the Great Cataract Group around Dry Falls was 3.5 miles (5.6 km) wide and 400 feet (122 m) tall. Imagine the roar of the ancient falls from the Dry Falls Visitor Center viewpoint off Washington State Route 17 between Coulee City and Sun Lakes-Dry Falls State Park.
DESCRIBING: A rectangular color photograph.
SYNOPSIS: A group of six people in mid-layers and light jackets sit on a grassy slope with their backs to the camera. They look out at a gentle, shallow valley blanketed in green grass under a partly cloudy sky. The valley is bordered by low ridges of dark rock. On the left-hand side of the channel, a butte of tan rock stands taller than the surrounding area.
IN-DEPTH DESCRIPTION: The rock butte seems to be made of three horizontal layers. The texture of the rock is rough, and chaotic, vertical columns can be made out from this distance. Beneath the butte a slope of loose rock tumbles into the gentle valley. Across the valley are less high, less dramatic ridges that are in shadow. In the distance, the land is green and flat, and the clouds cast a patchwork of shadow and light. In the foreground, three people sit in a row on a hill closest to the camera. On the left, a person in a blue raincoat and blue ball cap looks across the valley. Next to them, another person sits with their feet out in front of them. They wear long pants and hiking boots, with a long sleeve grey shirt under a red puffy vest. They have light skin and are slightly balding. Next to them sits a person with pale blonde hair and glasses wearing a long sleeve black shirt and a green puffy vest. Three more people sit in another row in front of the first row, and they appear slightly below the first three people due to the slope of the hill. On the far right is a person in a plaid flannel shirt. Next to them to the left a person with shoulder length brown hair lays back in the grass. To the far left sits a person with curly shoulder length grey hair and a long sleeve purple shirt.
CREDIT: Bruce Bjornstad
RELATED TEXT: As floodwaters from Grand Coulee emerged from Quincy Basin, they left behind “butte-and-basin scabland”—a landscape marked by hundreds of buttes surrounded by a network of braided channels. Known as the Drumheller Channels, they were the largest outlet of floodwaters from the Quincy Basin. Water, ice and debris eroded the topsoil and underlying basalt to create the channels, basins, potholes, and buttes. View this prime example of Ice Age Floods erosion at the Drumheller Channels National Natural Landmark (NNL) viewpoint 9.1 miles (14.6 km) northwest of Othello, Washington along McManamon Road.
DESCRIBING: A vertical rectangular color photograph.
SYNOPSIS: This image provides an aerial view of a waterfall that nestles in a canyon made up of black and brown rocks. Steep cliffs rise up around the waterfall, creating an amphitheater around the pool where the water collects down below.
IN-DEPTH DESCRIPTION: The waterfall plunges over a ledge about halfway up the cliffs. From this distance, it looks like a single thin stream of white water, which stands out against the stark landscape. The water in the pool at the base is dark blue to black, rippling out from the base of the waterfall. At the edges of the pool, thick green moss coats the rocky shore. The pool thins into a river as it flows downstream in the canyon, disappearing out of view. The cliffs surrounding the waterfall are weathered, covered in brown and orange lichen and clumps of dark green, brown, and tan shrubbery. On the closest cliff to the camera, the top of the cliff is almost black, with very few details visible in the muted light. At the top of the cliff is a tuft of dry grass the color of straw. The slope below is covered in bare, brown soil with scattered bunches of dry, yellow grasses. In the foreground wildflowers past their season bend over dry, beige grasses. In the background, past the cliffs and waterfall, undulating brown hills disappear into the distance under a grey, overcast sky.
CREDIT: NPS Katherine Person
RELATED TEXT: To the east of Drumheller Channels, another flood path showcases an active waterfall. Palouse Falls was created when floodwaters rerouted the ancestral Palouse River from flowing into the Columbia River and into its current course towards the Snake River. The Palouse River drops 200 feet (61 m) over a sheer cliff into a roiling bowl, then zigzags six miles (9.7 km) through the 300-foot (91 m) coulee cliffs of the Palouse River Canyon before flowing into the Snake River. View Palouse Falls from viewpoints at Palouse Falls State Park, 2.3 miles (3.7 km) east of Washington State Route 261.
DESCRIBING: A vertical rectangular color photo.
SYNOPSIS: Rocky hills dominate this image with the swirl of a river visible in the distance.
IN-DEPTH DESCRIPTION: In the foreground, dark brown grass provides spotty cover for a rocky hill. Farther below lie dark brown buttes. Straight ahead, the rock drops away and we see a wide blue river that winds along until it disappears behind tall brown buttes. Swathes of land can be seen in the distance, and a hazy sky shows through at the horizon. Sunlight hits the landscape to the left of the image, casting it in gold-red light.
CREDIT: Bruce Bjornstad
RELATED TEXT: All floodwaters crossing the Channeled Scabland funneled through a narrow two-mile-wide (3.2 km) gap in the Horse Heaven Hills called Wallula Gap. Like the neck of an hourglass, Wallula Gap restricted the flow of floodwaters along the Columbia River. As water, ice, and debris hit this constriction floodwaters backed up creating an enormous temporary hydraulic pond 900 feet (274 m) deep temporarily flooding Pasco Basin and its tributaries. See Wallula Gap by driving south on eastbound US 12 from Pasco, Washington. After crossing the Snake River, look for the gap across the Horse Heaven Hills to the south.
DESCRIBING: A vertical rectangular color photograph.
SYNOPSIS: A wide river flows through deep-cut mountains. In the foreground a concrete bridge extends across the image from left to right.
IN-DEPTH DESCRIPTION: This image shows a wide river starting in the left of the frame and extending to the center in between deep-cut, forested mountains. To the right of the river is a forested area with hints of a road cutting through. Further right is a thin meandering stream of water in a grassy stretch. The sky is thick with silver clouds marbling the sunlight that is able to pass through. In the foreground one can see a wet concrete bridge and road. Visible features of the bridge include a sidewalk, exterior walls, and two lamp posts.
CREDIT: NPS Katherine Person
RELATED TEXT: Past Wallula Gap, the Ice Age Floods overwhelmed the Columbia Gorge for 200 miles (322 km), creating alien-looking hoodoos and scablands, massive landslides, and giant gravel bars. As the churning, muddy waters rampaged, they stripped the river valley of rock and debris, dug pits, and tore massive basalt columns from the bedrock. A drive along Oregon’s Interstate 84 between Wallula Gap and Crown Point National Natural Landmark:—or a more leisurely drive along Washington State Route 14 that parallels I-84 between Plymouth and Vancouver—highlights the aftermath of these cataclysmic floodwaters. Along I-84, the Vista House atop Crown Point provides a stunning panorama.
DESCRIBING: A square color photograph.
SYNOPSIS: A large grey rock with a flat top is centered in the photo with green fields stretching behind it. Fluffy white clouds are scattered across the sky.
IN-DEPTH DESCRIPTION: A massive rock sits in the middle of a grassy field with no other similar rocks around it. Grass in front of the rock helps put it into scale, suggesting that it is 3-4 feet tall, and close to 10 feet long. The rock is shaded in tones of grey and black. It is surrounded by tall green grasses and short yellow-green grasses. The background contains expansive fields, a single blue mountain, and puffy grey-white clouds in a pale blue sky.
CREDIT: NPS Justin Radford
RELATED TEXT: Each time the Ice Age Floods overwhelmed the Columbia Gorge, they covered the lowlands of Oregon’s Willamette Valley with flood waters up to 400 feet (122 m) deep and left behind 200 feet (61m) of fertile sediment. The floods also left behind large icebergs from as far as the Northern Rocky Mountains, about 500 miles (805 km) away. Melting from within one of these icebergs was a 90-ton (82-metric ton) rock, also known as the Bellevue Erratic. Erratic Rock State Natural Site, six miles west of McMinnville on Oregon Route 18, is home to the Willamette valley’s largest glacial floods erratic. A short uphill hike takes visitors to sweeping views where they can imagine the immense amount of water that filled the valley below.
DESCRIBING: A square color photograph.
SYNOPSIS: A lighthouse with black and white horizontal stripes sits atop a grassy cliffside. It overlooks the grey-blue ocean with foamy waves crashing on the shore.
IN-DEPTH DESCRIPTION: Two grassy cliffsides appear on the left side of the image. The farthest cliff is dark and ominous, covered with vegetation and the silhouettes of trees. The closer of the two cliffsides is more in focus and features brown and tan grasses that stick up to form the impression of roughness. Standing on the farther cliff, the lighthouse has four alternating stripes of white and black with a lens rooms and peaked roof showing at the top. A small grey service building stands to the right of the lighthouse.
Beyond the cliffs is the stormy ocean. The water has a rippled texture. It is a medium grey-blue color, but in the distance, white waves form tunnels, leaving a white trail of water behind them. Closer to viewer, a line of foam can be seen where the waves curl over and slump back into the ocean. Up above, the sky is a hazy grey-blue color that transitions to lighter blue and then bright white in the upper right-hand corner of the image.
CREDIT: Aaron Webster
RELATED TEXT: Glacial floodwaters continued along the path of the Columbia River eventually reaching the Pacific Ocean. However, when the Ice Age Floods reached the mouth of the Columbia River, sea level was about 300 feet (91 m) lower than it is today. The dense, sediment-laden floodwaters created powerful currents that cut deeper into the Astoria Submarine Canyon across the continental shelf. These currents deposited massive amounts of sediment hundreds of miles offshore across the Astoria Deep Sea Fan and as far south as Cape Mendocino, California some 400 miles (644 km) away. Overlook the confluence of the Columbia River and the Pacific Ocean from Lewis and Clark Interpretive Center in Cape Disappointment State Park, Washington.
The back side of the brochure orients visitors in Exploring the Ice Age Floods. It provides a full-page, color map. This map shows spans Montana, Idaho, Washington, and Oregon, and shows modern day topography, roads, cities, towns, and sites of interest. It also shows the location of ice at the end of the ice age and the path of the flood waters, so as one travels across the region the user can compare their physical location with the overall story of the floods. There is a section of text at the bottom of the page containing information on planning your visit, which is captured in section 12 of this description.
Since the map contains a lot of information, after the initial overview description of the map, we have broken it down by state and region. Montana and Idaho can be found in the first section, followed by Washington in the second and Oregon in the third.
Within each region, we have split the information into three topics. The first topic is Topography and covers present day and Ice Age landscape features. Listen to this section to get a sense of the different geographic and geologic features on the map and how the story of the floods unfolds across the region being described. The second topic is Main Driving Route. Since the Ice Age Floods trail is a driving route, this is a more technical description of where exactly the roads go. Listen to this to follow the single main path that traces the floods from Montana to the Pacific Ocean. The third topic is the Loop and Spur Routes section. Listen to the Loop and Spur Routes section to hear about additional detours that can be taken along the way to explore more sites related to the floods.
DESCRIBING: A horizonal rectangle of a map.
SYNOPSIS: A map that conveys the glacial Lake Missoula floods over the landscape from Montana through Idaho, Washington, and Oregon. The map uses numbers and labels to point out major sites along the geologic trail, including towns and roads. Darker shading shows where the lake once existed and lighter shading indicates glacial floodwater and its pathway over the landscape.
DESCRIBING: Legend for the map.
SYNOPSIS: Red lines surrounded by pale yellow indicate the Main Ice Age Floods National Geologic Trail Route. Yellow lines surrounded by a thin black halo indicate the Loop and Spur Trail Route. Steel blue shading indicates Ancient Glacial Lakes. Light blue shading indicates the Area Impacted by Ice Age Flooding. The map is oriented with “north” pointing upward. This is indicated by a circle with an arrow pointing upwards. The map scale has a shorter horizontal black line that establishes a distance of 0 to 50 kilometers and a longer horizontal line that establishes a distance of 0 to 50 miles.
The right third of the map contains the northern portions of Montana and Idaho. Generally, these descriptions move right to left, following the course of the floods.
The states of Montana and Idaho occupy the right third of the map. Modern-day topography is shown as a beige shaded background, with high relief areas in lighter shades and low relief areas in darker colors. Imposed on top of this modern-day map are the locations of glaciers and water at the end of the last Ice Age. Dark blue markings indicate standing water while white indicates ice.
An ice sheet dominates the top half of the map. It is labelled “Cordilleran Ice Sheet” in bold blue letters across the top. Two major lobes of ice point southward from the main ice sheet and completely cover the modern-day mountains of northern Idaho and Montana, with fingers branching in all directions into the surrounding valleys. The eastern-most lobe of ice, labelled the Flathead Lobe, descends to meet a region of dark blue standing water. More ice extends westward from this point, forming a spider-like web in the lower valleys of Montana.
South of the Flathead Lobe stretches a large region of dark blue, which branches into low-relief valleys throughout southwestern Montana. Black text identifies this area as Glacial Lake Missoula. The lake extends predominantly north-south in the valleys between mountain ranges. Thinner sections of water connect the larger sections of the lake in an east-west direction. Even though the water fills multiple valleys all across the region, it’s important to note that all of this dark blue standing water is in some way connected. In total, this water covers a geographic area of 3,000 square miles.
At the modern-day Idaho-Montana border, the dark blue water of the lake hits another lobe of ice that keeps it from spreading farther to the west. A glacier descending from the north holds the water in place.
This lobe is self-contained. It is one branch, almost like an arm with a hand and fingers that spread downward and block the wide valleys in the narrowest part of Idaho. This feature is labelled the Purcell Trench Lobe. The modern-day town of Sandpoint, Idaho, is located within the Purcell Trench Lobe. Although this map shows the southbound glacier as a static entity, it would have advanced and retreated throughout the Ice Ages, damming up the water in Lake Missoula and setting the stage for the floods that will race westward across Washington and Idaho to the Pacific Ocean.
The Main Ice Age Floods National Geologic Trail Route is shown as a thick red line surrounded by a yellow halo. It starts outside Missoula, Montana, which is marked with a white circle outlined in black. Starting in the lower right corner of the map, two roads intersect in the town of Missoula. Running north and south is US Route 93. Moving from east to west is interstate 90. About 8 miles west of Missoula is a point of interest labeled “1. Lake Missoula Strandlines.” About ten miles along interstate 90, the Main Route turns north to follow US Route 93, Montana Highway 200, and Montana Highway 382 to a point of interest labeled “2. Camas Prairie Ripples.” Note that the journey between the first two points of interest is around 75 miles. After turning southwest onto Montana highway 28, one can return to Montana highway 200 and travel ten miles northwest to the next point of interest, which is labeled “3. Eddy Narrows.” Note that the distance between the second and third point of interest is less than 25 miles. A fourth point of interest is located about 75 miles farther northwest along Montana highway 200, which crosses the Idaho border. Twenty miles south of Montana Highway 200, there is a point of interest called “4. Glacial Dam at Green Monarch Ridge.”
The Main Ice Age Floods National Geologic Trail Route continues northwest to pass through Sandpoint, Idaho. Sandpoint is marked with a white circle outlined in black. The distance between Missoula and Sandpoint is about 200 miles. In Sandpoint, the Main Trail Route turns sharply south onto US Route 95 and continues approximately 25 miles to a sharp turn that divides the trail from the next point of interest. The Main Route continues west five miles, passing a point of interest labeled, “5. Missoula Floods Outburst Plain (Farragut State Park)” which lies about 5 miles east on Idaho State Highway 54. After visiting this point of interest, one can return to the Main Trail Route west and turn south onto Idaho State Highway 53. This highway will pass the Idaho border and become Washington State Route 290. At the border crossing, the road continues about 20 miles before it hits the third city on the route: Spokane, Washington. The distance from Sandpoint to Spokane is approximately 75 miles.
The Loop and Spur Trail Route is shown as a thick yellow line that starts south and east of Missoula, Montana. This route includes other paths that the floods took apart from their journey along the Main Ice Age Floods National Geologic Trail. Note that the main route often intersects the Loop and Spur Trail, but the loops and spurs constitute lesser-known areas carved out by the Ice Age Floods.
The Loop and Spur Route runs in two directions: South and north along US Route 93 and east and west along interstate 90. US Route 93 passes through Missoula before stopping about 35 miles north where Flathead Lake begins. About 8 miles west of Missoula is a point of interest labeled “1. Lake Missoula Strandlines.” The trail continues along Interstate 90, passing Missoula and carrying on for 50 miles before turning north and splitting Montana Highway 200. It then loops up and intersects with a point of interest labeled, “2. Camas Prairie Ripples.” At this point the Spur Route comes back around Flathead Lake and returns to Montana Highway 200.
Another spur of the Loop and Spur Route comes off Montana Highway 200, 15 miles east of the Idaho border going north for about 20 miles.
The next Loop Route starts in Sandpoint, Idaho, and runs west along state highway 2, following the Pend Oreille River. At the Idaho-Washington border, there is a split in the trail. One can either travel south for the Idaho loop, or cross the border to go to Spokane, Washington. Continuing from Spokane, one can turn south and drive for about 25 miles before hitting Interstate 90. Carry on past the geological features formed by the main lobe of ice that dammed Lake Missoula. Loop east for a short distance before turning north on US Route 95. Continue on US Route 95 to reach Sandpoint, thus completing the loop. Note that 20 miles north on US Route 95, one can travel east a mile to see a point of interest labeled, “5. Missoula Floods Outburst Plain (Farragut State Park)."
Washington state takes up around two thirds of the entire map. It is situated in the northwest corner of the map, to the west of Idaho and Montana and to the north of Oregon. This description will describe things moving roughly from right to left starting at the border of Washington and Idaho.
Washington state occupies approximately two-thirds of the overall map. Like the Montana and Idaho and Oregon sections, modern day topography is shown in beige. High relief areas are marked with lighter shades and low relief areas with darker shades. Imposed on top of this modern day map are the locations of glaciers and water as seen at the end of the last ice age. Dark blue areas indicate standing water while light blue area indicate areas impacted by the flood as the waters raced across the landscape. White areas indicate ice.
The top of the map is dominated by the ice sheet, which is labelled “Cordilleran Ice Sheet” in bold blue letters. Several significant lobes of ice descend from the north into present-day Washington state. We’ll follow the path of the floods as they continue from the Idaho-Washington border. In Idaho, a white lobe of ice called the Purcell Trench Lobe blocks standing water that lies farther to the east. An area of dark blue meanders west like a spiky serpent from modern-day Spokane. Standing water once covered this area, which is labeled “Glacial Lake Columbia.” In total, the region comprised approximately 1500 square miles. Immediately to the north of this glacial lake is a two-pronged lobe of ice labelled “Columbia River Lobe.” The western point of Glacial Lake Columbia reaches a massive lobe of ice labelled the “Okanogan Lobe.” There is no more water, standing or otherwise, indicated to the west of this lobe. There is massive amount of ice cover and associated tendrils, which reach into low-elevation valleys. About a third of the way inland from the Washington coastline is one section of glacial ice that extends south from the Cordilleran Ice Sheet into a rounded lobe. This is known as the Puget Lobe, indicating a section of ice sheet that once existed in Washington. Puget Lobe covers the modern-day cities of Seattle, Tacoma, and Olympia, Washington.
Moving back along the southern edge of Glacial Lake Columbia, a major transition happens. The dark blue of the standing water changes to the light blue of moving water. Here the text reads: “Floodwaters from Lake Missoula caused nearby Glacial Lake Columbia to overtop and flood the surrounding lowlands.”
The light blue color continues to the south in bands of braided channels. These channels flow to the southwest, racing away from Spokane, Idaho, and Glacial Lake Columbia. Large blue arrows also point towards the southwest, parallel with the channels of water. Black text covering the area reads “Channeled Scabland.” Further downstream, the water tends to take one of two distinct paths. The western and northern tract transitions from the channels into an open area of light blue water labelled “Quincy Basin.” The modern-day town of Moses Lake, Washington, is located here. This basin represents an area of slack water, where fast moving floodwater slowed down enough to pool into large regional lakes while still continuing to drain to lower elevations. Beneath the Quincy Basin is another unlabeled basin, shaped like an oval and extending horizontally west to east. Beneath that is the largest slack water area, which is labelled Pasco Basin. It is roughly the shape of a bow tie tilted at a 45-degree angle in a clockwise direction. The modern-day towns of Richland, Pasco, and Kennewick, Washington, are located at the mid-point of the bowtie part of this basin. The modern-day town of Walla Walla, Washington, is at the southeast point of the tilted bow. Another region of light blue slack water extends to the west like a long kidney bean attached to the midsection of the bowtie. This area is labelled Yakima Valley.
There is one other major path of floodwaters flowing from the Channeled Scablands south to the Pasco Basin. This route narrows to a small channel that follows the path of the current-day Snake River—a body of water that runs roughly east-west from Idaho into southeastern Washington. The light blue of the flood path travels eastward up the Snake River. As floodwater tried to follow this path, it reversed the flow of the Snake River before dead ending in present day Lewiston, Idaho and racing back westward down the Snake River into the Pasco Basin. Overall, the entire region described from Glacial Lake Columbia to the Pasco Basin, and across the entire width of the Channeled Scablands and slack-water basins is roughly 100 square miles.
The Main Ice Age Flood National Geologic Trail Route follows Washington State Route 290 from the Idaho border west to the city of Spokane, Washington. On the outskirts of the city sits a point of interest labeled, “6. Bowl and Pitcher State Park (Riverside State Park).” The Main Route continues west along US Route 2 for 35 miles before a Loop and Spur Route branches off to the north and south. The Main Route continues west for 29 miles, then connects with Washington State Route 174. The Main Route continues on Washington State Route 174 for 26 miles, where it passes through the Grand Coulee area, which is labeled, “Trail Headquarters (Lake Roosevelt NRA).” The Main Route continues south along Washington State Route 155 for 33 miles, then passes through a point of interest labeled, “7. Dry Falls at Grand Coulee (NNL) (Sun Lakes-Dry Falls State Park).” Another Loop and Spur Route branches off to the north and to the west. The Main Route continues south on Washington State Route 17 for 41 miles and passes through Moses Lake. From Moses Lake, the Main Route continues south for 45 miles, then joins US Route 395 for a few miles before turning onto Washington State Route 260 heading east. In 34 miles, the Main Route turns southeast onto Washington State Route 261. After ten miles it passes a point of interest labeled, “9. Palouse Falls (Palouse Falls State Park).” 22 miles farther south, the Main Route turns southwest on US Route 12 and heads towards Walla Walla for 46 miles. From Walla Walla, the Main Route continues west on US Route 12 for 31 miles before it arrives at a point of interest labeled, “10. Wallula Gap (NNL)”.
The Loop and Spur Trail Route in eastern Washington begins to branch away from the Main Trail Route in Spokane. One of the Spur Routes heads north through the remains of Glacial Lake Columbia, then continues 76 miles northeast to Sandpoint, Idaho. Another branch of the Spur Route heads south on US Route 95, traversing 105 miles from the city of Spokane to Lewiston, Idaho. From Lewiston, the Spur Route heads west on US Route 12, where it meets up with the Main Trail Route and continues to Walla Walla. North of Lewiston, along US Route 95 is a Spur Route option to loop back north from US State Route 195 to Washington State Route 271 and Washington State Route 27, which takes you back to Spokane. Another spur route heads southwest from Spokane along interstate 90 for 36 miles to Sprague, where it branches off again either southeast or northwest on Washington State Route 23. These routes lead through areas marked light blue on the map, indicating places impacted by the Ice Age floods. On the Lewiston branch of the Spur Route, there is an option to turn east on Washington State Route 26, which will lead past a point of interest labeled, “9. Palouse Falls (Palouse Falls State Park).”
Another portion of the Spur Route follows Washington State Route 23 north to Harrington and branches off further, either north on Washington State Route 28 to Davenport, or southwest to Soap Lake. From Davenport, the Spur Route follows State Route 25 north toward Fort Spokane, which lies at the confluence of the Spokane River and the Columbia River. There, the Spur Route loops around on the Miles Creston Road to return to State Route 25. A branch of the Spur Route heads south 36 miles from Washington State Route 174 toward Odessa, where it meets with another branch of the Spur Route that continues west to Soap Lake. From a point of interest labeled “7. Dry Falls at Grand Coulee (NNL),” the Spur Route branches off north on State Route 17. Next it turns west at State Route 172 to Chelan Falls. From Chelan Falls, it heads south on US Route 97 to the town of Orondo. From there, the traveler has two options. One option is to navigate east on US Route 2 from the town of Orondo back to State Route 17 at Sun Lakes-Dry Falls State Park. From Orondo, the traveler can also continue south on US Route 2 to Wenatchee. Continuing south from Wenatchee, they can follow State Route 28 to Palisades Road on the east side of State Route 28. They can take Palisades Road, which transitions to 24 NW Road. When that road intersects with B-SE Road, they can take B-SE north to link back to east US Route 2, which returns to Sun Lakes-Dry Falls State Park. Back on State Route 28, the traveler can also curve south and then east to the town of Quincy. From Quincy they have two options: They can head east on State Route 28 back to State Route 28 north, which links back to State Route 17 at Soap Lake, or head southwest on State Route 283 to the town of George. From Quincy, the user can head south on State Route 281 to the town of George. From the town of George, the Spur Loop Route heads southwest on Interstate 90 to the town of Vantage. From the town of Vantage, they can take State Route 26 all the way back to State Route 17. Backing up on State Route 26, they can also head north on State Route 262, which curves eastward back to State Route 17. Back on State Route 262, the Spur Route heads south to road 12 Southeast which turns into McManamon Road at a point of interest labeled, “8. Drumheller Channels (NNL).” McManamon Road will also take the traveler to the town of Othello and back onto State Route 17. After reaching the town of Vantage, the Spur Route follows Interstate 90 west to Ellensburg. From Ellensburg, the Spur Route can head south on State Route 28 to Yakima. From Yakima, the Spur Route heads east on State Route 24, which will turn northward and intersect State Route 243. The Spur route then heads west on State Route 243, which curves northward right back to the town of Vantage. Back in Yakima, the Spur Route can head south on Interstate 82 to the city of Richland. From Richland, The Spur Route follows Interstate 182 east to Pasco. From Pasco, US Route 395 will take travelers north to the intersection of State Route 17 and US Route 395. Back in Pasco, the Spur Route can head south back to the point of interest on the Main Trail Route labeled, “10. Wallula Gap (NNL).” Back in Richland, the traveler can continue on 82 southeast to the town of Kennewick. Interstate 82 continues south to the Washington-Oregon border.
Below Washington is the northern portion of Oregon, which features the Columbia River Gorge—a body of water flowing from the northeast side of Oregon to western Oregon and the Pacific Ocean.
Modern day Oregon occupies the bottom left side of the map, although most of the key sites and features occur along the state’s northern border with Washington. Like the Montana, Idaho, and Washington sections of the map, modern day topography is shown in beige, with high relief areas in lighter shades and low relief areas in darker colors. Imposed on top of this modern day map are the locations of water and ice at the end of the last ice age. Dark blue indicates standing water while light blue indicates areas impacted by the flood as the waters raced across the landscape. White indicates ice.
This section of audio description follows the Ice Age floods as they travel west along the Columbia River Gorge and pool in the Willamette Valley before entering the Pacific Ocean. The path of the floods crosses into modern day Oregon at Wallula Gap, a site of interest over two hundred miles directly inland from the Pacific Ocean. The light blue of moving water narrows to almost nothing here, representing a pinch point. This narrowing caused a bathtub effect, where water backed up into the Richland, Pasco, and Kennewick area, while still pushing to get through a narrow canyon on the Washington-Oregon border. Immediately south of Wallula Gap, the light blue of moving floodwaters widens again, and begins to flow westward at the Washington-Oregon border. The edges of the floodwaters extend north past the Washington border and south into Oregon and continue their journey west. A label over this area reads “Umatilla Basin.”
Continuing westward to the Pacific, the flood path narrows again before it crosses over the modern day city of the The Dalles. At this point the flood path is confined to a small region as it crosses through the Cascade Mountain range. The Cascade mountains are marked as a higher relief area via shading of light, high peaks and dark, deep valleys. This higher elevation area stretches vertically across the map, starting north of Washington in Canada and continuing south to where Oregon disappears off the map. To cross this region, the flood waters had to squeeze westward through a small gorge, surrounded by the high peaks of the Cascade Mountain range. The Columbia River Gorge, as this area is known, is around 70 miles long and on average 3 miles wide, so it appears on this map as a thin, curvy line flowing east to west toward Portland, Oregon.
Once free of the gorge, the floodwaters enter modern day Portland. The light blue of moving floodwater opens up again, extending south from Portland, away from the Washington border and south into Oregon proper. The waters rushed into low points in the landscape and briefly filled in the valley between the Cascade Mountain range and the Oregon Coastal range. On the map, light blue fills the low points in this valley, an area that is in total around 120 miles long and 20 to 40 miles wide. This area includes the locations of present day cities Corvallis and Salem. A label over this region reads “Willamette Valley.”
Back up north near Portland, after the light blue water widens, it continues to head north. At the town of Longview, about 50 miles north of Portland, it takes a sharp turn to the west. The flood path widens, until it reaches the ocean at present day Astoria. The light blue of moving water extends into the present day Pacific Ocean about 20 miles. Out from the point where the floodwaters emptied into the ocean, a dashed line continues north to south, curving to various distances from the present-day shoreline. The text here reads: “Dashed line indicates the approximate shoreline during the Ice Age Floods.”
Marked with a red and yellow line, the Main Ice Age Floods National Geologic Trail Route curves southwest below the Washington-Oregon border. The Main Trail Route intersects with a yellow line, which marks the Loop and Spur Trail Route. Here Interstate 82 crosses Washington state Route 14. Fifty miles west from the intersection, the Main Trail Route joins State Route 14 and follows it for 150 miles along the Columbia River. A white circle outlined in black indicates the location of The Dalles, which is nestled south of the Columbia River. The Main Route moves south through the Dalles, then continues 50 miles west to Interstate 84. For about another 150 miles, the Main Trail Route follows this interstate. It then splits. The northern route heads north over the border into Washington along interstate 5. About 50 miles northwest, the Main Trail goes through a circle outlined in black labeled Longview. For around 50 miles, the Main Trail Route curves west along the Columbia River until it joins Washington State Route 4. The Main Trail then curves up over the Columbia River and back down to the river. The route ends at the Pacific Coast. Here a point of interest is labeled, “13. Astoria Fan (Cape Disappointment State Park).”
Back at the split in Portland, the Main Trail Route jets southwest about 25 miles to Tualatin. Southwest about 10 miles, the Main Route joins Oregon Route 99W. The Main Trail Route continues another 50 miles southwest to a point of interest labeled, “12. Erratic Rock State Natural Site.” Below, the Main Route continues follows Oregon Route 18. The Main Route then continues southwest and turns abruptly southeast on Oregon Route 22. The Main Trail Route heads southeast, turns south for 50 miles to Corvallis. The Main Trail Route continues south for about 25 miles on Oregon route 99W. From there the Main Route continues south to Eugene.
The Loop and Spur Trail Route, marked in yellow, intersects the Main Ice Age Floods National Geologic Trail Route at the border where Interstate 82 crosses State Route 14. The Spur Trail Route makes an upside-down V at the intersection. The east route has a white road running parallel to it. Both roads lead to another Spur Trail Route that follows Interstate 84. The route heads 50 miles southeast to Pendleton. A white road continues 100 miles south. Another white road stretches from Pendleton about 200 miles southeast. This road has a label for Interstate 84. The west route of the upside-down V connects to Interstate 84. The Spur Trail Route then heads west for about 150 miles, following the Columbia River. Once the Main Route reaches The Dalles, it crosses north over state border between Washington and Oregon. The Spur Route then heads west along the Columbia River for 50 miles through State Route 14. The Spur Trail Route continues west for another 50 miles until it hits Interstate 5. The last ten miles of the Spur Route converge with the Main Trail Route. A point of interest is marked here as, “11. Columbia River Gorge National Scenic Area.” This point lies approximately 50 miles northwest of The Dalles. The Columbia River Gorge National Scenic Area encompasses 25 miles of landscape lying outside of Portland and on both sides of the Washington and Oregon border.
In Portland, the Spur Trail stretches 50 miles northwest, then fades into a white road winding toward the coast for another 75 miles. Where it fades, the Spur Route jets south for about 75 miles. Then it splits west and east for less than 10 miles before connecting to the Main Trail Route. The west side of the route continues 25 miles south to a corner on Oregon Route 22. The Spur Trail Route continues west for 10 miles, stopping in Salem. There, it splits in two and continues for about 50 miles northeast and comes together in Oregon City. The route continues north for about 10 miles, then loops back to Portland.
A separate section of the Spur Trail Route begins north of Longview before following US Route 30 west 50 miles to Astoria. Five miles north of Astoria, the Spur Route connects to the Main Trail Route. Other white roads head north to the Columbia River outlet, then head further south along the Pacific Coast and off the map.
Where Oregon Route 18 and US Route 20 meet together on the Main Trail Route, the Spur Trail Route heads west for less than 10 miles.
At the bottom of the map, a white road with a symbol indicating Interstate 5 stretches all the way to Tualatin and Oregon City, bypassing Eugene, Corvallis, and Salem. Interstate 5 continues for about 20 miles where it connects to the Main Trail Route. There is a white road connecting interstate 5 to Eugene that is less than 10 miles in length. A road of over 200 miles winds from the coast through Corvallis and crosses Interstate 5.
Follow the path of the Ice Age Floods through the fascinating landscape of some of the largest known floods in the geologic record. The Ice Age Floods National Geologic Trail is a driving route that leads you about 3,380 miles (5,439 km) through Montana, Idaho, Washington, and Oregon. The National Park Service manages the trail in collaboration with other federal agencies, state parks, private land owners, and the Ice Age Floods Institute.
Operating Hours: Because the Ice Age Floods National Geologic Trail includes dozens of parks, museums, and sites across four states, operating hours and seasons vary. We recommend calling sites to check their hours before visiting. Unstaffed sites are usually open from dawn to dusk. Find a list of parks and museums to visit at: www.nps.gov/iafl
Safety: Preparation is key to a successful visit. Please know your route. Not all routes are appropriate for large trailers or RVs. Some sites are remote, so have sufficient gas, drinking water, food, sun protection, layers of clothing, and other essential supplies as needed.
Fees and Permits: Fees and permits vary by location. Most federal public lands such as national parks, national forests, and lands managed by the Bureau of Reclamation honor the America the Beautiful National Parks and Federal Recreational Lands Pass. State parks throughout Montana, Idaho, Washington, and Oregon require entrance fees and/or parking passes. Information on state park passes can be found at:
StateParks.MT.gov
ParksAndRecreation.Idaho.gov
DiscoverPass.WA.gov
StateParks.Oregon.gov
Parking: Some sites may have very limited parking.
Leave No Trace: The Ice Age Floods National Geologic Trail highlights a significant geologic story. As you visit, help protect this national treasure by following Leave No Trace principles. Find more information at: LNT.org
Emergencies call 911
Learn More: Some sites have interpretive signs. Explore the trail’s website at www.nps.gov/iafl for additional information.
The Ice Age Floods Institute is an educational nonprofit organization dedicated to advocacy of the floods story. The institute was instrumental in the 2009 passage of federal legislation authorizing the National Park Service to establish the Ice Age Floods National Geologic Trail. Learn more about these magnificent floods on the institute’s website at: www.iafi.org
DESCRIBING: A vertical rectangular graphic logo.
SYNOPSIS: A graphic design containing the silhouette of a pine tree in a narrow river canyon. The tall canyon walls and tree are black, with a contrasting white sky background that blends into gray at the bottom of the image as it becomes a river flowing between the canyon walls. Beneath the graphic image are the words “NATIONAL NATURAL LANDMARKS PROGRAM” in black lettering.
IN-DEPTH DESCRIPTION: The silhouettes of jagged black canyon walls slope down from both sides of the image. On the left side of the canyon the silhouette of a pine tree sits on a rock promontory that juts out from the canyon wall. The black of the canyon walls become the outline of a winding river which appears to flow between the canyon walls. A white background contrasts with the walls and pine tree, then gradually darkens into a medium gray color and forms the winding river. Beneath the graphic image is a white box with black lettering which spell out the words “NATIONAL NATURAL LANDMARKS PROGRAM”.
RELATED TEXT:
Over 600 sites have been designated as National Natural Landmarks in recognition of their outstanding biological or geological features. They illustrate the diversity of the country’s landscape and tell the story of our natural heritage. Found in both rural and urban settings, some have public access while others do not. National Natural Landmarks highlight the location and significance of America’s natural features so that we may safeguard these sites today and in the future.
Eight sites along the Ice Age Floods National Geologic Trail are distinguished as National Natural Landmarks. They include: Glacial Lake Missoula in Montana; Drumheller Channels, Ginkgo Petrified Forest, Grand Coulee, The Great Gravel Bar of Moses Coulee, and Wallula Gap in Washington; and Crown Point and the Willamette Floodplain in Oregon.
Visit www.nps.gov/nnlandmarks for more information.
The Ice Age Floods National Geologic Trail is a partnership of dozens of parks, museums, and sites across four states. Accessibility varies by site. We recommend calling sites to ask about accommodation availability.
For up to date contact information for different sites, visit our website at www.nps.gov/iafl.