Dangerous roads cut through the landscape throughout the globe. There’s no getting around it. The state of Idaho certainly has its fair share, possible more, given its stunning mountainous terrain. This weekend (March 29, 2014) I gave a talk about the reasons for Idaho’s road placement at the Northwest Archaeological Conference. The paper combined two studies I completed over ten years ago:
1). Watercraft Distribution Throughout the Plateau Area, and
2). Idaho Roadcut Rockfall Hazard Classification System and Database.
It looks at the history of the region’s transportation with regard to its geography, culture and politics. Here is a synopsis of the talk, with some slides and other photographs.
Roadcut Hazard Study
The Idaho Roadcut Hazard Study included geographical, road feature, and use intensity. This photo was taken several miles east of Lewiston, Idaho.
The Idaho Roadcut Hazard Study included three years of field work examining roadcuts throughout the state of Idaho. I interviewed Idaho Transportation Department (ITD) maintenance staff (the roadcut hazard study was for and funded by ITD), who taught me their methods of examining the cut slopes and explained the issues that they had with roadcuts. The ITD maintenance staff also examined my study and resultant database over time so we could best include issues that they needed assessed. There are several, but they are generally summed up in the slide above: previous issues with the slope, geographic features that make them prone to failure, road use and intensity, weather (such as freeze/thaw, which expands and contracts the rock and soil), and road features, such as the tiny ditch underneath the overhanging cliff above it in the slide above.
Precarious Geology in a Couple of Photos
Two examples of cuts in precarious geological features are above: daylighting slope on the left, and soil/rock interface on the right.
Idaho has a fantastic array of geological features and history. It makes for a stunning landscape. It created the magnificent abundance of whitewater that attracts river runners throughout the world.
It also causes a lot of rockfall along Idaho’s roadways, both from natural causes and roadcuts. A couple of examples are depicted in the photograph above. The photograph on the left of the slide features a “daylighting” slope. The one on the left displays a contact between rock and soil (it shows a lot of other things too, but that’s another post). Explanations are below:
Daylighting slope: Basically, the slope of the cracks between rock masses tilt downward towards the road, but end above the road in the rock face….so there is nothing holding it back.
Rock/Soil Contact: During the roadcut study, I noticed that soil often seems very fragile near the rock/slope contact. Rock often (but not always) is too. I’d like to note that the roadcut shown above has since been cut waaaaayyy back from the road now. The last time I saw it (about ten years ago), a large pullout was there.
Roadway Changes Through Time
Thoroughfares changed for a variety of reasons over time.
Like a lot of other animals, human beings travel for a variety of reasons. These reasons change as are relationships evolve, our needs change, our technology improves, the people that live in an area move-in, move-out, or live with different groups with alternate values….in short, culture, geography, politics, and economics.
Elk Creek, depicted above, once had a wagon road crossing it that connected communities north of its banks to Orofino to the south. The crossing washed out, the communities to the north along the wagon road disappeared, but other communities popped up in other places. That wagon road is now a cool, short trail through the forest. That forest has overtaken the community ruins that lie along it, but signs mark the old building foundations, such as the school. The trail forks before reaching Elk Creek. The forks take hikers to the upper and lower falls. The trailhead starts not far from Bovill, Idaho.
Travel Before the Horse Entered Idaho
Before the horse entered the Plateau Culture Area after 1690, people primarily traveled by boat or by foot. Large meeting places were along waterways.
Before the horse entered (what is now) Idaho a few centuries ago, people traveled mostly by watercraft or on foot. Streams, lake and marshes snaked through the Pacific Northwest, creating a wide variety of trails, both for boats and for walking. Dogs were beasts of burden, transporting goods from one place to another. Snowshoes were used during the long winters in the mountains to traverse passes and other snowbound areas. People congregated to trade, socialize, and network in large groups during salmon season, often at enormous salmon fishing sites (Silverman 2003a).
The horse entered the Pacific Northwest in (what is now) southeastern Idaho around 1690 through 1700 (Haines 1938a, b). It spread northward, westward and eastward throughout the first half of the eighteenth century.
The horse entered Idaho sometime between 1690 and 1700. It spread westward and northward, then eastward throughout the first half of the eighteenth century (Haines 1938a, b). This altered travel in the region, particularly in areas less dominated by water than others.
After the Horse
The horse enabled people to travel longer distances in a shorter amount of time.
The horse carried people farther and faster to where they wanted to go. And the horse expanded their mobility and who they interacted with. Now people who lived in the middle of the Pacific Northwest could travel to the Plains and hunt bison, creating new friends and new competition for resources. Also, while horses needed water, they could cross larger expanses without it, as long as they could reach fresh grass (or other food) and water periodically. This freed people, particularly those who lived in the desert, from constant need for stream routes.
Newcomers, Politics, and Technology, Oh My!
The first European-Americans to enter the region were explorers. Lewis & Clark crossed the neck of the Idaho Panhandle. Other explorers, missionaries, settlers, and miners followed.
Lewis and Clark’s expedition crossed the northern portion of Idaho twice:
1). Westward through a Bitterroot mountain pass, then down the Lochsa and Clearwater in 1805.
2). On their return trip to Saint Louis, Missouri in 1806, they followed a similar path, but exploring other trails eastward.
Soon afterwards, settlers, missionaries, miners and other European Americans crossed the Oregon Trail (in what is now southern Idaho’s Snake River Plain).
With mining, politics, and economics came decisions to plow direct routes to mountains, connecting political and economic centers.
Although miners first headed towards gold fields in California and Canada, they eventually found ore of a variety of economically popular minerals throughout the Rocky Mountains. Roads needed to be built into them for access and transportation of both people and material items. Military roads, the largest being the Mullan Road, were constructed to connect the American West with eastern cities to protect the new settlers, miners, and economic interests (Silverman 2003b:5-8).
The state of Idaho itself was left over from whittling down the territories, finally gaining its current shape in 1868. This shape tightly surrounded numerous portions of the Rocky Mountains. It made travel within the state extraordinarily difficult. When people need to travel between the southern and northern portions of the state, they generally needed to traverse pathways around Idaho through Washington and Oregon, or Montana, which took a long time on a wagon trail (Silverman 2003b:5-8).
During the early 1900s, funding for the North – South Road (now SH 55 and US 95) came through. It was built upon the continental margin. This margin not only divided mountain ranges, but, in places, stood at the edge of the continental trough where mylonitic rocks abundantly filled the terrain (Aliberti and Manduca 1988). Mylonitic rocks contain very slick surfaces.
Roadcuts Through Precarious Terrain
Even roads that follow rivers are dangerous. Wider path with a cut slope an blind turns can be sketchy.
The new routes through slick, unstable rock, combined with old routes widened for new technology led to human-cut slopes. These newly formed cliffs no longer had rock anchoring them, preventing their failure. The roadcuts also exposed numerous cracks, which could cause rockfall on wagons and, later, automobiles.
Transportation department maintenance crews look after these slopes all over the state, and have since Idaho was a territory. However, the roadcut hazard survey was born of a need for greater tools to contend with these dangerous roads.
Synopsis of Factors Influencing Thoroughfare Placement
A change in priorities and culture: technology over geography, contributed to road placement in hazardous areas.
So what does it all mean? As time progressed, geography influenced road placement less and less. Politics and economics gradually dominated the determination of thoroughfares. All three factors: geography, politics, and economics played roles throughout time, but they switched in importance with one another. Quite possibly, this was due to who made the decisions, since the decision-makers changed over time. However, technological advances definitely affected travel routes within the same cultural group, as illustrated by the horse’s introduction to the region.
Aliberti, E.A., and C.A. Manduca
1988 A Transect Across An Island Arc-Continent Boundary in West-Central Idaho. In Guidebook to the Geology of Central and Southern Idaho, edited by P.K. Link and W.R. Hackett. Idaho Geological Survey Bulletin 27, pp. 99-107.
1938a Where Did the Plains Indians Get Their Horses? American Anthropologist 40(1):112-117.
1938b The Northward Spread of Horses Among the Plains Indians. American Anthropologist 40(3):429-437.
Silverman, Shari Maria
2003a Watercraft Distribution Throughout the Plateau Culture Area. Unpublished Master of Arts Thesis for the Anthropology and Sociology Department and College of Graduate Studies. University of Idaho, Moscow, Idaho.
2003b Idaho Roadcut Rockfall hazard Classification System and Database. Unpublished Master of Science Thesis for the Civil Engineering Department and College of Graduate Studies. University of Idaho, Moscow, Idaho.
Idaho Transportation Culture Seen Through Roadcuts by Shari Maria Silverman is licensed under a Creative Commons Attribution 4.0 International License.